Fix handling of usual deallocation functions in various configuratios.

Clang allows users to enable or disable various types of allocation
and deallocation regardless of the C++ dialect. When extended new/delete
overloads are enabled in older dialects, we need to treat them as if
they're usual.

Also, disabling one usual deallocation form shouldn't
disable any others. For example, disabling aligned allocation in C++2a
should have no effect on destroying delete.

llvm-svn: 352980