DebugInfo: Move DIType::is*() queries to MDType

Move body of `DIType::isObjectPointer()` (etc.) to `MDType`, and change
the versions in `DIType` to forward there.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234275 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed