[llvm] [X86] remove unnecessary movs when %rdx is an input to mulx (PR #184462)

[Takashi Idobe via llvm-commits]

Takashiidobe wrote:

Thanks for the review. I see CI passed for linux :tada: but failed for windows :disappointed: 
Looks like some linker errors? I think clang-format isn't properly linked:

https://github.com/llvm/llvm-project/actions/runs/22647626757/job/65679172330?pr=184462#step:4:34722

```lld-link: error: undefined symbol: public: __cdecl clang::tooling::IncludeCategoryManager::IncludeCategoryManager(struct clang::tooling::IncludeStyle const &, class llvm::StringRef)```

https://github.com/llvm/llvm-project/pull/184462