[llvm] Enable the use of SCCache for debug builds on Windows (PR #82371)

[Martin Storsjö via llvm-commits]

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@@ -10,3 +10,9 @@ endif()
 if(POLICY CMP0116)
   cmake_policy(SET CMP0116 OLD)
 endif()
+
++# Enable debug info compatible with SCCache
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mstorsjo wrote:

This explains the end goal of why we're adding this policy here, at this time, but it doesn't say anything to the reader about what `CMP0141` really does. (Yes, the reader can google it, but it's good with a quick reference here inline.) Can you do a 1-2 line brief summary of what it changes, like for the other policies above (and mention in which CMake version it was introduced)? It's fine to keep the end motivation for why we're adding it though.

https://github.com/llvm/llvm-project/pull/82371