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.

The module currently stores the target triple as a string. This means
that any code that wants to actually use the triple first has to
instantiate a Triple, which is somewhat expensive. The change in #121652
caused a moderate compile-time regression due to this. While it would be
easy enough to work around, I think that architecturally, it makes more
sense to store the parsed Triple in the module, so that it can always be
directly queried.

For this change, I've opted not to add any magic conversions between
std::string and Triple for backwards-compatibilty purses, and instead
write out needed Triple()s or str()s explicitly. This is because I think
a decent number of them should be changed to work on Triple as well, to
avoid unnecessary conversions back and forth.

The only interesting part in this patch is that the default triple is
Triple("") instead of Triple() to preserve existing behavior. The former
defaults to using the ELF object format instead of unknown object
format. We should fix that as well.

Summary:
This is supposed to be `__llvm_rpc_client` but I screwed it up and
didn't notice at the time. Will need to be backported.

Summary:
Currently, we only use `-mlink-builtin-bitcode` for non-LTO NVIDIA
compiliations. This has the problem that it will internalize the RPC
client symbol which needs to be visible to the host. To counteract that,
I put `retain` on it, but this also prevents optimizations on the global
itself, so the passes we have that remove the symbol don't work on
OpenMP anymore. This patch does the dumbest solution, adding a special
string check for it in clang. Not the best solution, the runner up would
be to have a clang attribute for `externally_initialized` because those
can't be internalized, but that might have some unfortunate
side-effects. Alternatively we could make NVIDIA compilations do LTO all
the time, but that would affect some users and it's harder than I
thought.

In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing includes that were previously included transitively
through this header.

This is fixing all files missed in b0abd4893fa1.

Differential Revision: https://reviews.llvm.org/D154543

Mostly removing includes of InitializePasses.h and Pass.h in
passes that no longer has support for the legacy PM.

Follow up to c41c336ee065a

Internalize was trying to update CallGraph if the analysis was available, but the new PM doesn't really use it so there's little reason to update it.