Pretty print support for template arg enum constants

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@224184 91177308-0d34-0410-b5e6-96231b3b80d8
NFC: Minor formatting fix

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@224185 91177308-0d34-0410-b5e6-96231b3b80d8