PR14558: Compute triviality of special members (etc) at the end of the class

PR14558: Compute triviality of special members (etc) at the end of the class
definition, rather than at the end of the definition of the set of nested
classes. We still defer checking of the user-specified exception specification
to the end of the nesting -- we can't check that until we've parsed the
in-class initializers for non-static data members.

llvm-svn: 169805