This gets Windows ARM64 to compile with clang-cl, which gives up to 40% performance improvements in certain scenes rendered with cycles, compared to MSVC.
This is all tested using LLVM 18.1.8 and a VS2022 `vcvarsall` window.
Subsequent PRs with various lib version updates, etc to go in at a later point.
Pull Request: https://projects.blender.org/blender/blender/pulls/124182
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