OpenACC deviceptr clause: Fix handling in Fortran.

OpenACC deviceptr clause: Fix handling in Fortran.

With two gcc_asserts restored, and not handling OpenACC deviceptr clauses in
the same data paths as other OpenACC data clauses, we'd run into an internal
compiler error, when the deviceptr clause is used with (non-offloaded) OpenACC
data regions:

    FAIL: gfortran.dg/goacc/data-tree.f95   -O  (internal compiler error)
    FAIL: gfortran.dg/goacc/data-tree.f95   -O  (test for excess errors)

	gcc/fortran/
	* gfortran.h (OMP_LIST_DEVICEPTR): Remove, and instead...
	(enum gfc_omp_map_op): ... add OMP_MAP_FORCE_DEVICEPTR here.
	* dump-parse-tree.c (show_omp_clauses): Update.
	* openmp.c (gfc_match_omp_clauses, resolve_omp_clauses)
	(gfc_resolve_oacc_declare): Likewise.
	* trans-openmp.c (gfc_trans_omp_clauses): Likewise.
	gcc/
	* omp-low.c (lower_omp_target): Restore two gcc_asserts.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gomp-4_0-branch@217352 138bc75d-0d04-0410-961f-82ee72b054a4