This patch transforms:

  X && *X == Y

to:

  X == Y

where X is of std::optional<T>, and Y is of T or similar.

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 patch addresses clang-tidy's readability-const-return-type by
dropping const from the return type while switching to StringRef at
the same time because these functions just return string constants.

Currently BlockAddresses store both the Function and the BasicBlock they
reference, and the BlockAddress is part of the use list of both the
Function and BasicBlock.

This is quite awkward, because this is not really a use of the function
itself (and walks of function uses generally skip block addresses for
that reason). This also has weird implications on function RAUW (as that
will replace the function in block addresses in a way that generally
doesn't make sense), and causes other peculiar issues, like the ability
to have multiple block addresses for one block (with different
functions).

Instead, I believe it makes more sense to specify only the basic block
and let the function be implied by the BB parent. This does mean that we
may have block addresses without a function (if the BB is not inserted),
but this should only happen during IR construction.

DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range.  This patch replaces:

  Dest.insert(Src.begin(), Src.end());

with:

  Dest.insert_range(Src);

This patch does not touch custom begin like succ_begin for now.

Summary:
This code is intended to block transformations if the call isn't
present, however the way it's coded it silently lets it pass if the
definition doesn't exist at all. This previously was always valid since
we included the runtime as one giant blob so everything was always
there, but now that we want to move towards separate ones, it's not
quite correct.

Add initial parsing/sema support for new assumption clause so clause can
be specified. For now, it's ignored, just like the others.

Added support for 'no_openmp_construct' to release notes.

Testing
- Updated appropriate LIT tests.
- Testing: check-all