OpenMP: Add omp_all_memory support to Fortran

OpenMP: Add omp_all_memory support to Fortran

Fortran part to the C/C++/backend implementation
r13-337-g7f78783dbedca0183d193e475262ca3c489fd365

gcc/fortran/ChangeLog:

	* dump-parse-tree.cc (show_omp_namelist): Handle omp_all_memory.
	* openmp.cc (gfc_match_omp_variable_list, gfc_match_omp_depend_sink,
	gfc_match_omp_clauses, resolve_omp_clauses): Likewise.
	* trans-openmp.cc (gfc_trans_omp_clauses, gfc_trans_omp_depobj):
	Likewise.
	* resolve.cc (resolve_symbol): Reject it as symbol.

libgomp/ChangeLog:

	* libgomp.texi (OpenMP 5.1): Set omp_all_memory to 'Y'.
	* testsuite/libgomp.fortran/depend-5.f90: New test.
	* testsuite/libgomp.fortran/depend-6.f90: New test.
	* testsuite/libgomp.fortran/depend-7.f90: New test.

gcc/testsuite/ChangeLog:

	* gfortran.dg/gomp/all-memory-1.f90: New test.
	* gfortran.dg/gomp/all-memory-2.f90: New test.
	* gfortran.dg/gomp/all-memory-3.f90: New test.