Fortran/OpenMP: Fix privatization of associated names

Fortran/OpenMP: Fix privatization of associated names

gfc_omp_predetermined_sharing cases the associate-name pointer variable
to be OMP_CLAUSE_DEFAULT_FIRSTPRIVATE, which is fine. However, the associated
selector is shared. Thus, the target of associate-name pointer should not get
copied. (It was before but because of gfc_omp_privatize_by_reference returning
false, the selector was not only wrongly copied but this was also not done
properly.)

gcc/fortran/ChangeLog:

	PR fortran/103039
	* trans-openmp.cc (gfc_omp_clause_copy_ctor, gfc_omp_clause_dtor):
	Only privatize pointer for associate names.

libgomp/ChangeLog:

	PR fortran/103039
	* testsuite/libgomp.fortran/associate4.f90: New test.