re PR c++/88554 (Segfault ICE when falling off the end of a reference-returning friend operator)

	PR c++/88554
	* decl.c (finish_function): For -Wreturn-type don't add a return *this;
	fixit hint if current_class_ref is NULL.  Use a single if instead of
	two nested ones.

	* g++.dg/warn/Wreturn-type-11.C: New test.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r267672