[clang] [llvm] [LoongArch] Add support for half-precision floating-point type (PR #141564)

[Lu Weining via llvm-commits]

SixWeining wrote:

LLVM uses squash and merge. So please split it into 3 PRs if you do not want to squash them.

https://github.com/llvm/llvm-project/pull/141564