Diagnose uses of deleted destructors and inaccessible defaulted destructors.

We had two separate issues here: firstly, varions functions were assuming that
they did not need to perform semantic checks on trivial destructors (this is
not true in C++11, where a trivial destructor can nonetheless be private or
deleted), and a bunch of DiagnoseUseOfDecl calls were missing for uses of
destructors.

llvm-svn: 150866