release/20.x: [modules] Handle friend function that was a definition but became only a declaration during AST deserialization (#132214)#134232

dmpolukhin wants to merge 3 commits intollvm:release/20.xllvm/llvm-project:release/20.xfrom

dmpolukhin:friend-default-parameters-llvm-20.xdmpolukhin/llvm-project:friend-default-parameters-llvm-20.xCopy head branch name to clipboard