cobol: Support SET of NUMERIC type for GnuCOBOL emulation.

gcc/cobol/ChangeLog:

	* cbldiag.h (enum cbl_diag_id_t): Add MfSetNumeric and sort alphabetically.
	* cobol1.cc (cobol_langhook_handle_option): Handle OPT_Wset_numeric.
	* gcobol.1: Document Wset-numeric option.
	* lang-specs.h: Add Wset-numeric to specs string.
	* lang.opt: Add Wset-numeric option.
	* messages.cc: Add MfSetNumeric to mf and gnu dialects, and sort alphabetically.
	* parse_ante.h (parser_move_carefully): Report diagnotic per dialect.