[llvm] [llvm-lib] Handle MIPS architecture (PR #121254)

[Hervé Poussineau via llvm-commits]

hpoussin wrote:

@wzssyqa : this is the same as https://github.com/llvm/llvm-project/pull/121007 , but I disabled a test if MIPS target is not registered.

https://github.com/llvm/llvm-project/pull/121254