* errors.c: New file; defines functions error, warning, and
fatal, variables have_error and progname.
* errors.h: New file; prototypes and decls for stuff in errors.c.
* Makefile: Add rules to build errors.o and
$(HOST_PREFIX)errors.o. Link genconfig, gencodes, genemit,
genopinit, genrecog, genextract, genpeep, genattr, and
genoutput with errors.o. Add errors.h to deps of genconfig.o,
gencodes.o, genemit.o, genopinit.o, genrecog.o, genextract.o,
genpeep.o, genattr.o, and genoutput.o.
* genconfig.c, gencodes.c, genemit.c, genopinit.c, genrecog.c,
genextract.c, genpeep.c, genattr.c: Include errors.h. Don't
define or prototype fatal. Set progname at beginning of main.
* genoutput.c: Likewise, and don't define or prototype error
either.