[llvm] [NVPTX] Make GlobalUniqueCallSite a member of NVPTXISelLowering (PR #130212)

[Artem Belevich via llvm-commits]

Artem-B wrote:

OK, so it's not exactly a race condition, but rather compilation stability in multi-threaded compilation.

I'd rephrase the patch description along the lines of "make call site enumeration local to individual compilation, which ensures that call site numbers are consistently sequential within each compilation and is independent of other compilations happening in parallel".

https://github.com/llvm/llvm-project/pull/130212