[llvm] [JITLink][LoongArch] Add R_LARCH_{B16, B21} relocations support (PR #121096)

[David Spickett via llvm-commits]

DavidSpickett wrote:

FYI, this uncovered a problem on 32-bit hosts which I fixed in https://github.com/llvm/llvm-project/commit/5cf138cfbaa8040100fed1d0d5e0a189759b24ab.

https://github.com/llvm/llvm-project/pull/121096