These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

This flag was used to let us incrementally introduce debug records
into LLVM, however everything is now using records. It serves no
purpose now, so delete it.

Specifically this is the assertion in BasicBlock.cpp. Now that we're not
examining or setting that flag consistently (because it'll be deleted in
about an hour) there's no need to keep this assertion.

Original commit title:

[DebugInfo][RemoveDIs] Remove some debug intrinsic-only codepaths (#143451)

By chance, two things have prevented the autoupgrade path being
exercised much so far:
 * LLParser setting the debug-info mode to "old" on seeing intrinsics,
* The test in AutoUpgrade.cpp wanting to upgrade into a "new" debug-info
block.

In practice, this appears to mean this code path hasn't seen the various
invalid inputs that can come its way. This commit does a number of
things:
* Tolerates the various illegal inputs that can be written with
debug-intrinsics, and that must be tolerated until the Verifier runs,
 * Printing illegal/null DbgRecord fields must succeed,
* Verifier errors need to localise the function/block where the error
is,
 * Tests that now see debug records will print debug-record errors,

Plus a few new tests for other intrinsic-to-debug-record failures modes
I found. There are also two edge cases:
* Some of the unit tests switch back and forth between intrinsic and
record modes at will; I've deleted coverage and some assertions to
tolerate this as intrinsic support is now Gone (TM),
* In sroa-extract-bits.ll, the order of debug records flips. This is
because the autoupgrader upgrades in the opposite order to the basic
block conversion routines... which doesn't change the record order, but
_does_ change the use list order in Metadata! This should (TM) have no
consequence to the correctness of LLVM, but will change the order of
various records and the order of DWARF record output too.

I tried to reduce this patch to a smaller collection of changes, but
they're all intertwined, sorry.

Start removing debug intrinsics support -- starting with the flag that
controls production of their replacement, debug records. This patch
removes the command-line-flag and with it the ability to switch back to
intrinsics. The module / function / block level "IsNewDbgInfoFormat"
flags get hardcoded to true, I'll to incrementally remove things that
depend on those flags.

## Purpose

This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `llvm/IR`,
`llvm/IRPrinter`, and `llvm/IRReader` libraries. These annotations
currently have no meaningful impact on the LLVM build; however, they are
a prerequisite to support an LLVM Windows DLL (shared library) build.

## Background

This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).

The bulk of these changes were generated automatically using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool, followed formatting with `git clang-format`.

The following manual adjustments were also applied after running IDS on
Linux:
- Add `#include "llvm/Support/Compiler.h"` to files where it was not
auto-added by IDS due to no pre-existing block of include statements.
- Add `LLVM_ABI_FRIEND` to friend member functions declared with
`LLVM_ABI`
- Add `LLVM_TEMPLATE_ABI` and `LLVM_EXPORT_TEMPLATE` to exported
instantiated templates
- Add `LLVM_ABI` to a subset of private class methods and fields that
require export
- Add `LLVM_ABI` to a small number of symbols that require export but
are not declared in headers
- Reorder `LLVM_ABI` with `[[deprecated]]` and `[[nodiscard]]`
attributes.

## Validation

Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:

- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang

splitBasicBlock inserts an unconditional branch in the "before" block to
the "after" block. It copies the DebugLoc from the split point. Prevent
it copying the source location atom.

Add unittest.

RFC:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668

BasicBlock currently has a blockaddress refcount. However,
blockaddresses are uniqued, which means that there can only be a single
blockaddress for a given BasicBlock. Prior to #137958 there were some
edge case exceptions to this, but now it always holds. As such, replace
the refcount with a single flag.

As we're now just tracking two bits, I've dropped the BasicBlockBits
structure, as I found it more annoying than useful (esp with the weird
AIX workarounds). Instead handle the subclass data the same way we do in
Operators.

Don't repeatedly replaceAllUsesWith in a loop.