[clang] [compiler-rt] [clang][DebugInfo] Add inlined subprogram metadata for compiler built-ins (PR #189969)

[J. Ryan Stinnett via llvm-commits]

jryans wrote:

I believe this is now ready for another round of review. (Now that it is out of draft mode, I will only append commits going forward, as expected by the code review policy.)

The primary change compared to the initial version is the various classes of built-ins that now opt-out of this treatment for various reasons (see summary in [PR description](https://github.com/llvm/llvm-project/pull/189969#issue-4187472261)).

In addition, I have also added an enabled-by-default flag to control this behaviour. It can be disabled with `-gno-inlined-builtins` when needed.

https://github.com/llvm/llvm-project/pull/189969