[llvm] Give a warning when no dwo files are provided (PR #94336)

[Alexander Yermolovich via llvm-commits]

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@@ -0,0 +1,218 @@
+# Note: This file is compiled from the following code, for 
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ayermolo wrote:

small nit. I think it's now ##

https://github.com/llvm/llvm-project/pull/94336