[llvm] [test] Skip some tests on Windows only (PR #95205)

[via llvm-commits]

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@@ -1,4 +1,6 @@
-# REQUIRES: shell
+# This test uses symlinks.
+UNSUPPORTED: system-windows
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zmodem wrote:

I think we need the leading `#`?

https://github.com/llvm/llvm-project/pull/95205