c++: Fix ICE with weird copy assignment operator [PR114572]

c++: Fix ICE with weird copy assignment operator [PR114572]

While ctors/dtors don't return anything (undeclared void or this pointer
on arm) and copy assignment operators normally return a reference to *this,
it isn't invalid to return uselessly some class object which might need
destructing, but the OpenMP clause handling code wasn't expecting that.

The following patch fixes that.

2024-04-05  Jakub Jelinek  <jakub@redhat.com>

	PR c++/114572
	* cp-gimplify.cc (cxx_omp_clause_apply_fn): Call build_cplus_new
	on build_call_a result if it has class type.

	* testsuite/libgomp.c++/pr114572.C: New test.

(cherry picked from commit 592536eb3c0a97a55b1019ff0216ef77e6ca847e)