Merge non-contiguous array support patches.

Merge non-contiguous array support patches.

This version is based from v4, posted upstream here:
https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543437.html

2020-04-19  Chung-Lin Tang  <cltang@codesourcery.com>

	PR other/76739

	gcc/c/
	* c-typeck.cc (handle_omp_array_sections_1): Add 'bool &non_contiguous'
	parameter, adjust recursive call site, add cases for allowing
	pointer based multi-dimensional arrays for OpenACC.
	(handle_omp_array_sections): Adjust handle_omp_array_sections_1 call,
	handle non-contiguous case to create dynamic array map.

	gcc/cp/
	* semantics.cc (handle_omp_array_sections_1): Add 'bool &non_contiguous'
	parameter, adjust recursive call site, add cases for allowing
	pointer based multi-dimensional arrays for OpenACC.
	(handle_omp_array_sections): Adjust handle_omp_array_sections_1 call,
	handle non-contiguous case to create dynamic array map.

	gcc/fortran/
	* f95-lang.cc (DEF_FUNCTION_TYPE_VAR_5): New symbol.
	* types.def (BT_FN_VOID_INT_SIZE_PTR_PTR_PTR_VAR): New type.

	gcc/
	* builtin-types.def (BT_FN_VOID_INT_SIZE_PTR_PTR_PTR_VAR): New type.
	* omp-builtins.def (BUILT_IN_GOACC_DATA_START): Adjust function type
	to new BT_FN_VOID_INT_SIZE_PTR_PTR_PTR_VAR.
	* gimplify.cc (gimplify_scan_omp_clauses): Skip gimplification of
	OMP_CLAUSE_SIZE of non-contiguous array maps (which is a TREE_LIST).
	* omp-expand.cc (expand_omp_target): Add non-contiguous array descriptor
	pointers to variadic arguments.
	* omp-low.cc (append_field_to_record_type): New function.
	(create_noncontig_array_descr_type): Likewise.
	(create_noncontig_array_descr_init_code): Likewise.
	(scan_sharing_clauses): For non-contiguous array map kinds, check for
	supported dimension structure, and install non-contiguous array
	variable into current omp_context.
	(reorder_noncontig_array_clauses): New function.
	(scan_omp_target): Call reorder_noncontig_array_clauses to place
	non-contiguous array map clauses at beginning of clause sequence.
	(lower_omp_target): Add handling for non-contiguous array map kinds,
	add all created non-contiguous array descriptors to
	gimple_omp_target_data_arg.

	gcc/testsuite/
	* c-c++-common/goacc/noncontig_array-1.c: New test.

	libgomp/
	* libgomp_g.h (GOACC_data_start): Add variadic '...' to declaration.
	* libgomp.h (gomp_map_vars_openacc): New function declaration.
	* oacc-int.h (struct goacc_ncarray_dim): New struct declaration.
	(struct goacc_ncarray_descr_type): Likewise.
	(struct goacc_ncarray): Likewise.
	(struct goacc_ncarray_info): Likewise.
	(goacc_noncontig_array_create_ptrblock): New function declaration.
	* oacc-parallel.c (goacc_noncontig_array_count_rows): New function.
	(goacc_noncontig_array_compute_sizes): Likewise.
	(goacc_noncontig_array_fill_rows_1): Likewise.
	(goacc_noncontig_array_fill_rows): Likewise.
	(goacc_process_noncontiguous_arrays): Likewise.
	(goacc_noncontig_array_create_ptrblock): Likewise.
	(GOACC_parallel_keyed): Use goacc_process_noncontiguous_arrays to
	handle non-contiguous array descriptors at end of varargs, adjust
	to use gomp_map_vars_openacc.
	(GOACC_data_start): Likewise. Adjust function type to accept varargs.
	* target.c (gomp_map_vars_internal): Add struct goacc_ncarray_info *
	nca_info parameter, add handling code for non-contiguous arrays.
	(gomp_map_vars_openacc): Add new function for specialization of
	gomp_map_vars_internal for OpenACC structured region usage.
	* testsuite/libgomp.oacc-c-c++-common/noncontig_array-1.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/noncontig_array-2.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/noncontig_array-3.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/noncontig_array-4.c: New test.
	* testsuite/libgomp.oacc-c-c++-common/noncontig_array-utils.h: Support
	header for new tests.

	include/
	* gomp-constants.h (GOMP_MAP_FLAG_SPECIAL_3): Define.
	(enum gomp_map_kind): Add GOMP_MAP_NONCONTIG_ARRAY,
	GOMP_MAP_NONCONTIG_ARRAY_TO, GOMP_MAP_NONCONTIG_ARRAY_FROM,
	GOMP_MAP_NONCONTIG_ARRAY_TOFROM, GOMP_MAP_NONCONTIG_ARRAY_FORCE_TO,
	GOMP_MAP_NONCONTIG_ARRAY_FORCE_FROM, GOMP_MAP_NONCONTIG_ARRAY_FORCE_TOFROM,
	GOMP_MAP_NONCONTIG_ARRAY_ALLOC, GOMP_MAP_NONCONTIG_ARRAY_FORCE_ALLOC,
	GOMP_MAP_NONCONTIG_ARRAY_FORCE_PRESENT.
	(GOMP_MAP_NONCONTIG_ARRAY_P): Define.