StopInfoBreakpoint keeps a BreakpointLocationCollection for all the
breakpoint locations at the BreakpointSite that was hit. It is also
lives through the time a given thread is stopped, so there are plenty of
opportunities for one of the owning breakpoints to get deleted.

But BreakpointLocations don't keep their owner Breakpoints alive, so if
the BreakpointLocationCollection can live past when some code gets a
chance to delete an owner breakpoint, and then you ask that location for
some breakpoint information, it will access freed memory.

This wasn't a problem before PR #158128 because the StopInfoBreakpoint
just kept the BreakpointSite that was hit, and when you asked it
questions, it relooked up that list. That was not great, however,
because if you hit breakpoints 5 & 6, deleted 5 and then asked which
breakpoints got hit, you would just get 6. For that and other reasons
that PR changed to storing a BreakpointLocationCollection of the
breakpoints that were hit. That's better from a UI perspective but
caused this potential problem.

I fix it by adding a variant of the BreakpointLocationCollection that
also holds onto a shared pointer to the Breakpoints that own the
locations that were hit, thus keeping them alive till the
StopInfoBreakpoint goes away.

This fixed the ASAN assertion. I also added a test that works harder to
cause trouble by deleting breakpoints during a stop.

This patch adds the notion of "Facade" locations which can be reported
from a ScriptedResolver instead of the actual underlying breakpoint
location for the breakpoint. Also add a "was_hit" method to the scripted
resolver that allows the breakpoint to say which of these "Facade"
locations was hit, and "get_location_description" to provide a
description for the facade locations.

I apologize in advance for the size of the patch. Almost all of what's
here was necessary to (a) make the feature testable and (b) not break
any of the current behavior.

The motivation for this feature is given in the "Providing Facade
Locations" section that I added to the python-reference.rst so I won't
repeat it here.

rdar://152112327

This is something the StopInfo class manages, so it should be allowed to
compute this rather than having SBThread do so. This code just moves the
computation to methods in StopInfo. It is mostly NFC. The one change
that I actually had to adjust the tests for was a couple of tests that
were asking for the UnixSignal stop info data by asking for the data at
index 1. GetStopInfoDataCount returns 1 and we don't do 1 based indexing
so the test code was clearly wrong. But I don't think it makes sense to
perpetuate handing out the value regardless of what index you pass us.

Use std::make_shared to create a StopInfoSP, which inherits from
shared_from_this. It's both the most efficient and safest way to create
these objects:

- With make_shared, the object and the control block are allocated
together, which is more efficient.
- With make_shared, the enable_shared_from_this base class is properly
linked to the control block before the constructor finishes, so
shared_from_this() will be safe to use (though still not recommended
during construction).

LLDB breakpoint conditions take an expression that's evaluated using the
language of the code where the breakpoint is located. Users have asked
to have an option to tell it to evaluate the expression in a specific
language.

This is feature is especially helpful for Swift, for example for a
condition based on the value in memory at an offset from a register.
Such a condition is pretty difficult to write in Swift, but easy in C.

This PR adds a new argument (-Y) to specify the language of the
condition expression. We can't reuse the current -L option, since you
might want to break on only Swift symbols, but run a C expression there
as per the example above.

rdar://146119507

This is necessary so that LLDB does not select (or show the stop reason
for) a thread which stopped at an internal breakpoint.

Other than manual testing/inspection, which I've done, this does not
seem to lend itself to API testing, as we cannot set internal
breakpoints through the SBAPI.

This NFC patch simplifies the main loop in HandleProcessStateChanged
event by moving duplicated code into the StopInfo class, also allowing
StopInfo subclasses to override behavior.

More specifically, two functions are created:

* ShouldShow: should a Thread with such StopInfo should be printed when
the debugger stops? Currently, no StopInfo subclasses override this, but
a subsequent patch will fix a bug by making StopInfoBreakpoint check
whether the breakpoint is internal.

* ShouldSelect: should a Thread with such a StopInfo be selected? This
is currently overridden by StopInfoUnixSignal but will, in the future,
be overridden by StopInfoBreakpoint.

This reverts commit
https://github.com/llvm/llvm-project/commit/87b7f63a117c340a6d9ca47959335fd7ef6c7ad2,
reapplying

https://github.com/llvm/llvm-project/commit/7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b
with a small (and probably temporary)
change to generate more debug info to help with diagnosing buildbot
issues.

Make StreamAsynchronousIO an unique_ptr instead of a shared_ptr. I tried
passing the class by value, but the llvm::raw_ostream forwarder stored
in the Stream parent class isn't movable and I don't think it's worth
changing that. Additionally, there's a few places that expect a
StreamSP, which are easily created from a StreamUP.

lldb today has two rules: When a thread stops at a BreakpointSite, we
set the thread's StopReason to be "breakpoint hit" (regardless if we've
actually hit the breakpoint, or if we've merely stopped *at* the
breakpoint instruction/point and haven't tripped it yet). And second,
when resuming a process, any thread sitting at a BreakpointSite is
silently stepped over the BreakpointSite -- because we've already
flagged the breakpoint hit when we stopped there originally.

In this patch, I change lldb to only set a thread's stop reason to
breakpoint-hit when we've actually executed the instruction/triggered
the breakpoint. When we resume, we only silently step past a
BreakpointSite that we've registered as hit. We preserve this state
across inferior function calls that the user may do while stopped, etc.

Also, when a user adds a new breakpoint at $pc while stopped, or changes
$pc to be the address of a BreakpointSite, we will silently step past
that breakpoint when the process resumes. This is purely a UX call, I
don't think there's any person who wants to set a breakpoint at $pc and
then hit it immediately on resuming.

One non-intuitive UX from this change, butt is necessary: If you're
stopped at a BreakpointSite that has not yet executed, you `stepi`, you
will hit the breakpoint and the pc will not yet advance. This thread has
not completed its stepi, and the ThreadPlanStepInstruction is still on
the stack. If you then `continue` the thread, lldb will now stop and
say, "instruction step completed", one instruction past the
BreakpointSite. You can continue a second time to resume execution.

The bugs driving this change are all from lldb dropping the real stop
reason for a thread and setting it to breakpoint-hit when that was not
the case. Jim hit one where we have an aarch64 watchpoint that triggers
one instruction before a BreakpointSite. On this arch we are notified of
the watchpoint hit after the instruction has been unrolled -- we disable
the watchpoint, instruction step, re-enable the watchpoint and collect
the new value. But now we're on a BreakpointSite so the watchpoint-hit
stop reason is lost.

Another was reported by ZequanWu in
https://discourse.llvm.org/t/lldb-unable-to-break-at-start/78282 we
attach to/launch a process with the pc at a BreakpointSite and
misbehave. Caroline Tice mentioned it is also a problem they've had with
putting a breakpoint on _dl_debug_state.

The change to each Process plugin that does execution control is that

1. If we've stopped at a BreakpointSite that has not been executed yet,
we will call Thread::SetThreadStoppedAtUnexecutedBP(pc) to record that.
When the thread resumes, if the pc is still at the same site, we will
continue, hit the breakpoint, and stop again.

2. When we've actually hit a breakpoint (enabled for this thread or
not), the Process plugin should call
Thread::SetThreadHitBreakpointSite(). When we go to resume the thread,
we will push a step-over-breakpoint ThreadPlan before resuming.

The biggest set of changes is to StopInfoMachException where we
translate a Mach Exception into a stop reason. The Mach exception codes
differ in a few places depending on the target (unambiguously), and I
didn't want to duplicate the new code for each target so I've tested
what mach exceptions we get for each action on each target, and
reorganized StopInfoMachException::CreateStopReasonWithMachException to
document these possible values, and handle them without specializing
based on the target arch.

I first landed this patch in July 2024 via
https://github.com/llvm/llvm-project/pull/96260

but the CI bots and wider testing found a number of test case failures
that needed to be updated, I reverted it. I've fixed all of those issues
in separate PRs and this change should run cleanly on all the CI bots
now.

rdar://123942164