Fortran: Add LOCALITY support for DO_CONCURRENT

	This patch provided by Anuj Mohite as part of the GSoC project.
	It is modified slightly by Jerry DeLisle for minor formatting.
	The patch provides front-end parsing of the LOCALITY specs in
	DO_CONCURRENT and adds numerous test cases.

gcc/fortran/ChangeLog:

	* dump-parse-tree.cc (show_code_node):  Updated to use
	c->ext.concur.forall_iterator instead of c->ext.forall_iterator.
	* frontend-passes.cc (index_interchange): Updated to
	use c->ext.concur.forall_iterator instead of c->ext.forall_iterator.
	(gfc_code_walker): Likewise.
	* gfortran.h (enum locality_type): Added new enum for locality types
	in DO CONCURRENT constructs.
	* match.cc (match_simple_forall): Updated to use
	new_st.ext.concur.forall_iterator instead of new_st.ext.forall_iterator.
	(gfc_match_forall): Likewise.
	(gfc_match_do):  Implemented support for matching DO CONCURRENT locality
	specifiers (LOCAL, LOCAL_INIT, SHARED, DEFAULT(NONE), and REDUCE).
	* parse.cc (parse_do_block): Updated to use
	new_st.ext.concur.forall_iterator instead of new_st.ext.forall_iterator.
	* resolve.cc (struct check_default_none_data): Added struct
	check_default_none_data.
	(do_concur_locality_specs_f2023): New function to check compliance
	with F2023's C1133 constraint for DO CONCURRENT.
	(check_default_none_expr): New function to check DEFAULT(NONE)
	compliance.
	(resolve_locality_spec): New function to resolve locality specs.
	(gfc_count_forall_iterators): Updated to use
	code->ext.concur.forall_iterator.
	(gfc_resolve_forall): Updated to use code->ext.concur.forall_iterator.
	* st.cc (gfc_free_statement): Updated to free locality specifications
	and use p->ext.concur.forall_iterator.
	* trans-stmt.cc (gfc_trans_forall_1): Updated to use
	code->ext.concur.forall_iterator.

gcc/testsuite/ChangeLog:

	* gfortran.dg/do_concurrent_10.f90: New test.
	* gfortran.dg/do_concurrent_8_f2018.f90: New test.
	* gfortran.dg/do_concurrent_8_f2023.f90: New test.
	* gfortran.dg/do_concurrent_9.f90: New test.
	* gfortran.dg/do_concurrent_all_clauses.f90: New test.
	* gfortran.dg/do_concurrent_basic.f90: New test.
	* gfortran.dg/do_concurrent_constraints.f90: New test.
	* gfortran.dg/do_concurrent_local_init.f90: New test.
	* gfortran.dg/do_concurrent_locality_specs.f90: New test.
	* gfortran.dg/do_concurrent_multiple_reduce.f90: New test.
	* gfortran.dg/do_concurrent_nested.f90: New test.
	* gfortran.dg/do_concurrent_parser.f90: New test.
	* gfortran.dg/do_concurrent_reduce_max.f90: New test.
	* gfortran.dg/do_concurrent_reduce_sum.f90: New test.
	* gfortran.dg/do_concurrent_shared.f90: New test.

Signed-off-by: Anuj <anujmohite001@gmail.com>