[clang] [clang][ASTImporter] Remove 'hasReturnTypeDeclaredInside' (PR #169504)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Based on the summary this makes sense but can you point to the change that fixed this so we can have more context?

https://github.com/llvm/llvm-project/pull/169504