[clang] [lld] [llvm] [clang][MIPS] Add support for mipsel-windows-* targets (PR #107744)

[Hervé Poussineau via llvm-commits]

hpoussin wrote:

Current list of PRs to have a usable toolchain (except linker):
- #120876 [MC][Mips] Generate required IMAGE_REL_MIPS_PAIR relocation
- #120877 [MC][CodeGen][Mips] Add CodeView mapping
- #120912 [Mips] Handle declspec(dllimport) on mipsel-windows-* triples
- #121041 [Clang][MIPS] Create correct linker arguments for Windows toolchains
- #121042 [Clang][MIPS] Send correct architecture for MinGW toolchains
- #121254 [llvm-lib] Handle MIPS architecture

https://github.com/llvm/llvm-project/pull/107744