[flang] [clang] [libc] [compiler-rt] [clang-tools-extra] [llvm] [lld] [lldb] [libcxx] [NVPTX] Add support for -march=native in standalone NVPTX (PR #79373)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Got it, okay, thanks.
> 
> Since this change only applies to `--target=nvptx64-nvidia-cuda`, fine by me. Thanks for putting up with our scrutiny. :)

No problem, I probably should've have been  clearer in my commit messages.

https://github.com/llvm/llvm-project/pull/79373