[clang] Use cmake to find perl executable (PR #91275)

[Matthias Braun via cfe-commits]

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@@ -1,4 +1,4 @@
-REQUIRES: shell
+REQUIRES: perl
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MatzeB wrote:

Seems there is `rm` but no `ls`:  https://github.com/MatzeB/llvm-project/blob/5e5b18a31057f0d086ce9731d2b58aa70d55eef5/llvm/utils/lit/lit/TestRunner.py?plain=1#L714

https://github.com/llvm/llvm-project/pull/91275