[llvm] [TypeMetadataUtil][CallPromtionUtil]Add utility function getFunctionAtVTableOffset that finds functions through alias. Use it in CallPromotionUtils which didn't promote aliasee previously (PR #80736)

[Teresa Johnson via llvm-commits]

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@@ -14,6 +14,7 @@
 #ifndef LLVM_ANALYSIS_TYPEMETADATAUTILS_H
 #define LLVM_ANALYSIS_TYPEMETADATAUTILS_H
 
+#include "llvm/IR/GlobalVariable.h"
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teresajohnson wrote:

Can you instead just use a forward declaration for GlobalVariable, like we do for other types below?

https://github.com/llvm/llvm-project/pull/80736