OpenACC 2.6 deep copy: middle-end parts

	gcc/
	* gimplify.c (gimplify_omp_var_data): Add GOVD_MAP_HAS_ATTACHMENTS.
	(insert_struct_comp_map): Support derived-type member mappings
	for arrays with descriptors which use GOMP_MAP_TO_PSET.  Support
	GOMP_MAP_ATTACH_DETACH.
	(gimplify_scan_omp_clauses): Tidy up OACC_ENTER_DATA/OACC_EXIT_DATA
	mappings.  Handle attach/detach clauses and component references.
	(gimplify_adjust_omp_clauses_1): Skip adjustments for explicit
	attach/detach clauses.
	(gimplify_omp_target_update): Handle struct mappings and finalize for
	detach operations.
	* omp-low.c (lower_omp_target): Support GOMP_MAP_ATTACH,
	GOMP_MAP_DETACH, GOMP_MAP_FORCE_DETACH.
	* tree-pretty-print.c (dump_omp_clause): Likewise, plus
	GOMP_MAP_ATTACH_DETACH.

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

From-SVN: r279626