[llvm] [clang] [LoongArch] Add definitions and feature 'frecipe' for FP approximation intrinsics/builtins (PR #78962)

[Lu Weining via cfe-commits]

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

LGTM if the conflicting were resolved.

https://github.com/llvm/llvm-project/pull/78962