[clang] [llvm] [LoongArch] [CodeGen] Add options for Clang to generate LoongArch-specific frecipe & frsqrte instructions (PR #109917)

[Lu Weining via cfe-commits]

https://github.com/SixWeining approved this pull request.

LGTM except a nit.

https://github.com/llvm/llvm-project/pull/109917