[Clang] Emit KCFI type hashes for member functions

With `-fsanitize=kcfi`, Clang currently won't emit type hashes for
C++ member functions, which leads to check failures if they are
indirectly called. As there's no reason to exclude member functions
in CodeGenModule::setKCFIType, emit type hashes also for them to fix
member function pointer calls with KCFI, and add a test to confirm
that types are emitted correctly.