* gensupport.c (init_md_reader_args_cb): Renamed from
	init_md_reader_args.  Add third option, callback function for
	parsing program-specific options.  Add diagnosis of incorrect
	number of input files.
	(init_md_reader): Fold into init_md_reader_args_cb.
	(init_md_reader_args): Now a thin wrapper around
	init_md_reader_args_cb.
	* gensupport.h: Update prototypes.

	* genattr.c, genattrtab.c, gencodes.c, genconfig.c, genemit.c
	* genextract.c, genflags.c, genopinit.c, genoutput.c, genpeep.c
	* genrecog.c: No need to diagnose lack of an input file;
	init_md_reader_args will handle it.
	* genconditions.c: Likewise, and use init_md_reader_args.
	* genconstants.c: Likewise, and no need to call read_md_rtx.

From-SVN: r85511