OpenMP/Fortran: Fix unmapping of GOMP_MAP_POINTER for scalar allocatables/pointers

OpenMP/Fortran: Fix unmapping of GOMP_MAP_POINTER for scalar allocatables/pointers

target exit data: Do unmap GOMP_MAP_POINTER for scalar allocatables/pointers
to prevent stale mappings.

While for allocatable/pointer arrays, there is a PSET followed by POINTER,
for allocatable/pointer scalars there is only a POINTER. Before the below
mentioned OG12 patch: For exit data, PSET was converted to RELEASE/DELETE
in gimplify.cc while all POINTER were removed; correct for arrays but leaving
POINTER behind for scalars. Since that commit, all in trans-openmp.cc but
the scalar case was still mishandled before this follow-up commit.

This is a follow up to OG12's 55a18d4744258e3909568e425f9f473c49f9d13f
While the problem is independent, it will be merged into v4 of the
mainline patch
'Fortran/OpenMP: Fix mapping of array descriptors and deferred-length strings'

gcc/fortran/

	* trans-openmp.cc (gfc_trans_omp_clauses): Fix unmapping of
	GOMP_MAP_POINTER for scalar allocatables/pointers.

gcc/testsuite/

	* gfortran.dg/gomp/map-10.f90: New test.