[clang] [clang-format] Fix `check-format-depends` CMake for Windows (PR #209205)

[via cfe-commits]

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@@ -43,12 +43,15 @@ file(GLOB_RECURSE files
 
 set(check_format_depends clang-format)
 find_program(DIFF_EXE diff)
-if(DIFF_EXE)
+find_program(TOUCH_EXE touch)
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owenca wrote:

Is there a real-world setup that has `diff` but not `touch`?

https://github.com/llvm/llvm-project/pull/209205