[clang] [PowerPC] Fix use of FPSCR builtins in smmintrin.h (PR #67299)

[Stefan Pintilie via cfe-commits]

https://github.com/stefanp-ibm approved this pull request.

I'm going to approve this patch.
I don't think that removing the mask `__fpscr_save.__fpscr &= 0x70007f0ffL;`  in `smmintrin.h` with have issues but I don't feel strongly enough about it to block this patch. If you are not convinced that it is safe you can leave the masks in. 

LGTM.

https://github.com/llvm/llvm-project/pull/67299