Add CXXRecordDecl::forallBases to walk an inheritance hierarchy with non-lookup

semantics and CXXRecordDecl::isProvablyNotDerivedFrom to assist with
pre-instantiation diagnostics.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90842 91177308-0d34-0410-b5e6-96231b3b80d8