Use the same tag type across all PointerLikeTypeTraits specializations

Works around a bug (PR28216) in Clang's MS mangling of templates with
partial specializations.

This mismatch was introduced in about six months ago in r256656.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273223 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed