AST: small cleanup to FriendObjectKind


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185021 91177308-0d34-0410-b5e6-96231b3b80d8
This patch fixes PR16395, when HandleMSProperty returns null due to a declaration with no name.

Patch thanks to Robert Wilhelm.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185022 91177308-0d34-0410-b5e6-96231b3b80d8