Make the Twine pretty-printer work with GDB 7.11

Apparently ::NodeKind is sometimes part of the name in GDB.
Without this patch I get the following error message from GDB:
`Unhandled NodeKind llvm::Twine::NodeKind::EmptyKind`.

Patch by Alexander Richardson!

Differential Revision: https://reviews.llvm.org/D32795

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304675 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed