[clang] [Clang] Support multilibs on Windows (PR #200212)

[Yaxun Liu via cfe-commits]

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@@ -314,6 +314,9 @@ Non-comprehensive list of changes in this release
 
 - Updated support for Unicode from 15.1 to 18.0.
 
+- Linux and Windows toolchains now support Clang multilib support
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yxsamliu wrote:

This wording is a bit awkward because of "support ... support", and it also sounds like Linux support is newly added here. Maybe make it more specific, e.g. "Windows MSVC toolchains now support Clang multilib configuration via `--multi-lib-config=` and `-fmultilib-flag=`."

https://github.com/llvm/llvm-project/pull/200212