Fortran: Handle compare in OpenMP atomic

Fortran: Handle compare in OpenMP atomic

gcc/fortran/ChangeLog:

	PR fortran/103576
	* openmp.c (is_scalar_intrinsic_expr): Fix condition.
	(resolve_omp_atomic): Fix/update checks, accept compare.
	* trans-openmp.c (gfc_trans_omp_atomic): Handle compare.

libgomp/ChangeLog:

	* libgomp.texi (OpenMP 5.1): Set Fortran support for atomic to 'Y'.
	* testsuite/libgomp.fortran/atomic-19.f90: New test.

gcc/testsuite/ChangeLog:

	* gfortran.dg/gomp/atomic-25.f90: Remove sorry, fix + add checks.
	* gfortran.dg/gomp/atomic-26.f90: Likewise.
	* gfortran.dg/gomp/atomic-21.f90: New test.