[opaque pointer types] Add an explicit value type to GlobalObject

This is needed by all GlobalObjects (GlobalAlias, Function,
GlobalVariable), see the GlobalObject::getValueType which is used in
many places. If at some point that can be removed, then we can remove
this member.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247621 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed