optimize, to follow the permissions granted in N3664. Under those rules, only
calls generated by new-expressions and delete-expressions are permitted to be
optimized, and direct calls to ::operator new and ::operator delete must be
treated as normal calls.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@186799 91177308-0d34-0410-b5e6-96231b3b80d8