Support Fortran 2003 class pointers in OpenACC

Support Fortran 2003 class pointers in OpenACC

	gcc/
	* gimplify.c (insert_struct_comp_map): Handle GOMP_MAP_ATTACH_DETACH.
	(gimplify_scan_omp_clauses): Separate out handling of OACC_ENTER_DATA
	and OACC_EXIT_DATA. Remove GOMP_MAP_POINTER and GOMP_MAP_TO_PSET
	mappings, apart from those following GOMP_MAP_DECLARE_{,DE}ALLOCATE.
	Handle GOMP_MAP_ATTACH_DETACH.
	* tree-pretty-print.c (dump_omp_clause): Support GOMP_MAP_ATTACH_DETACH.
	Print "bias" not "len" for attach/detach clause types.

	include/
	* gomp-constants.h (gomp_map_kind): Add GOMP_MAP_ATTACH_DETACH.

	gcc/c/
	* c-typeck.c (handle_omp_array_sections): Use GOMP_MAP_ATTACH_DETACH
	for OpenACC attach/detach operations.

	gcc/cp/
	* semantics.c (handle_omp_array_sections): Likewise.
	(finish_omp_clauses): Handle GOMP_MAP_ATTACH_DETACH.

	gcc/fortran/
	* openmp.c (resolve_oacc_data_clauses): Allow polymorphic allocatable
	variables.
	* trans-expr.c (gfc_conv_component_ref,
	conv_parent_component_reference): Make global.
	(gfc_auto_dereference_var): New function, broken out of...
	(gfc_conv_variable): ...here. Call outlined function instead.
	* trans-openmp.c (gfc_trans_omp_array_section): New function, broken out
	of...
	(gfc_trans_omp_clauses): ...here. Separate out OpenACC derived
	type/polymorphic class pointer handling. Call above outlined function.
	* trans.h (gfc_conv_component_ref, conv_parent_component_references,
	gfc_auto_dereference_var): Add prototypes.

	gcc/testsuite/
	* c-c++-common/goacc/mdc-1.c: Update clause matching patterns.

	libgomp/
	* oacc-parallel.c (GOACC_enter_exit_data): Fix optional arguments for
	changes to clause stripping in enter data/exit data directives.
	* testsuite/libgomp.oacc-fortran/class-ptr-param.f95: New test.
	* testsuite/libgomp.oacc-fortran/classtypes-1.f95: New test.
	* testsuite/libgomp.oacc-fortran/classtypes-2.f95: New test.
	* testsuite/libgomp.oacc-fortran/derivedtype-1.f95: New test.
	* testsuite/libgomp.oacc-fortran/derivedtype-2.f95: New test.
	* testsuite/libgomp.oacc-fortran/multidim-slice.f95: New test.

(cherry picked from openacc-gcc-9-branch commit
3c260613f2e74d6639c4dbd43b018b6640ae8454)