Make argv const char ** in read_md_files etc

Make argv const char ** in read_md_files etc

gcc/ChangeLog:
	* genattr-common.c (main): Convert argv from
	char ** to const char **.
	* genattr.c (main): Likewise.
	* genattrtab.c (main): Likewise.
	* genautomata.c (initiate_automaton_gen): Likewise.
	(main): Likewise.
	* gencodes.c (main): Likewise.
	* genconditions.c (main): Likewise.
	* genconfig.c (main): Likewise.
	* genconstants.c (main): Likewise.
	* genemit.c (main): Likewise.
	* genenums.c (main): Likewise.
	* genextract.c (main): Likewise.
	* genflags.c (main): Likewise.
	* genmddeps.c (main): Likewise.
	* genopinit.c (main): Likewise.
	* genoutput.c (main): Likewise.
	* genpeep.c (main): Likewise.
	* genpreds.c (main): Likewise.
	* genrecog.c (main): Likewise.
	* gensupport.c (init_rtx_reader_args_cb): Likewise.
	(init_rtx_reader_args): Likewise.
	* gensupport.h (init_rtx_reader_args_cb): Likewise.
	(init_rtx_reader_args): Likewise.
	* gentarget-def.c (main): Likewise.
	* read-md.c (read_md_files): Likewise.
	* read-md.h (read_md_files): Likewise.

From-SVN: r235976