OpenMP 5.1: Add proc-bind 'primary' support

OpenMP 5.1: Add proc-bind 'primary' support

In OpenMP 5.1 "master thread" was changed to "primary thread" and
the proc_bind clause and the OMP_PROC_BIND environment variable
now take 'primary' as argument as alias for 'master', while the
latter is deprecated.
This commit accepts 'primary' and adds the named constant
omp_proc_bind_primary and changes 'master thread' in the
documentation; however, given that not even OpenMP 5.0 is
fully supported, omp_display_env and the dumps currently
still output 'master' and there is no deprecation warning
when using the 'master' in the proc_bind clause.

gcc/c/ChangeLog:

	* c-parser.c (c_parser_omp_clause_proc_bind): Accept
	'primary' as alias for 'master'.

gcc/cp/ChangeLog:

	* parser.c (cp_parser_omp_clause_proc_bind): Accept
	'primary' as alias for 'master'.

gcc/fortran/ChangeLog:

	* gfortran.h (gfc_omp_proc_bind_kind): Add OMP_PROC_BIND_PRIMARY.
	* dump-parse-tree.c (show_omp_clauses): Add TODO comment to
	change 'master' to 'primary' in proc_bind for OpenMP 5.1.
	* intrinsic.texi (OMP_LIB): Mention OpenMP 5.1; add
	omp_proc_bind_primary.
	* openmp.c (gfc_match_omp_clauses): Accept
	'primary' as alias for 'master'.
	* trans-openmp.c (gfc_trans_omp_clauses): Handle
	OMP_PROC_BIND_PRIMARY.

gcc/ChangeLog:

	* tree-core.h (omp_clause_proc_bind_kind): Add
	OMP_CLAUSE_PROC_BIND_PRIMARY.
	* tree-pretty-print.c (dump_omp_clause): Add TODO comment to
	change 'master' to 'primary' in proc_bind for OpenMP 5.1.

libgomp/ChangeLog:

	* env.c (parse_bind_var): Accept 'primary' as alias for
	'master'.
	(omp_display_env): Add TODO comment to
	change 'master' to 'primary' in proc_bind for OpenMP 5.1.
	* libgomp.texi: Change 'master thread' to 'primary thread'
	in line with OpenMP 5.1.
	(omp_get_proc_bind): Add omp_proc_bind_primary and note that
	omp_proc_bind_master is an alias of it.
	(OMP_PROC_BIND): Mention 'PRIMARY'.
	* omp.h.in (__GOMP_DEPRECATED_5_1): Define.
	(omp_proc_bind_primary): Add.
	(omp_proc_bind_master): Deprecate for OpenMP 5.1.
	* omp_lib.f90.in (omp_proc_bind_primary): Add.
	(omp_proc_bind_master): Deprecate for OpenMP 5.1.
	* omp_lib.h.in (omp_proc_bind_primary): Add.
	* testsuite/libgomp.c/affinity-1.c: Check that
	'primary' works and is identical to 'master'.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/pr61486-2.c: Duplicate one proc_bind(master)
	testcase and test proc_bind(primary) instead.
	* gfortran.dg/gomp/affinity-1.f90: Likewise.