[clang] [clang] Support -Wa, options -mmsa and -mno-msa (PR #99615)

[Fangrui Song via cfe-commits]

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@@ -0,0 +1,8 @@
+// RUN: %clang -### -c --target=mips64el-unknown-linux-gnuabi64 \
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MaskRay wrote:

We don't need -fno-integrated-as tests. They are just forwarded.

The -mmsa test needs a NOT. I'll push a commit to improve the test

https://github.com/llvm/llvm-project/pull/99615