[clang] LoongArch fp16,fp128 basic support (PR #68851)

[WÁNG Xuěruì via cfe-commits]

https://github.com/xen0n commented:

Thanks for the contribution and welcome!

As for the commit message, please take a look at the existing commits for the general feel. (For example, people typically prefix the commit title with the involved topic(s) in brackets, and use a verb phrase for the remaining.)

Besides, the LLVM side of the change lacks a test case; you can look at the other targets for reference.

https://github.com/llvm/llvm-project/pull/68851