[clang] [compiler-rt] [XRay] Add support for instrumentation of DSOs on x86_64 (PR #90959)

[Sebastian Kreutzer via cfe-commits]

sebastiankreutzer wrote:

I rebased on upstream `main` again and tested locally.  
@MaskRay Let me know if you have further comments or concerns.

https://github.com/llvm/llvm-project/pull/90959