[MS ABI] Workaround corner-case bug in the ABI for operator delete

MSVC only genreates array cookies if the class has a destructor.  This
is problematic when having to call T::operator delete[](void *, size_t)
because the second argument's argument is impossible to synthesize
correctly if the class has no destructor (because there will be no array
cookie).

Instead, MSVC passes the size of the class.  Do the same, for
compatibility, instead of crashing.

This fixes PR23990.

llvm-svn: 241038