PointerLikeTypeTraits: class->struct & remove the base definition

This simplifies implementations and removing the base definition paves
the way for detecting whether a type is 'pointer like'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310507 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed