fortran: Add support for per-location warning groups.

gcc/fortran/ChangeLog:

	* trans-array.c (trans_array_constructor): Replace direct uses
	of TREE_NO_WARNING with warning_suppressed_p, and suppress_warning.
	* trans-decl.c (gfc_build_qualified_array): Same.
	(gfc_build_dummy_array_decl): Same.
	(generate_local_decl): Same.
	(gfc_generate_function_code): Same.
	* trans-openmp.c (gfc_omp_clause_default_ctor): Same.
	(gfc_omp_clause_copy_ctor): Same.
	* trans-types.c (get_dtype_type_node): Same.
	(gfc_get_desc_dim_type): Same.
	(gfc_get_array_descriptor_base): Same.
	(gfc_get_caf_vector_type): Same.
	(gfc_get_caf_reference_type): Same.
	* trans.c (gfc_create_var_np): Same.