* Makefile.in (BISON): Add comment that when bison is used, it

	* Makefile.in (BISON):  Add comment that when bison is used, it
	must include the "-y" option.
	* c-exp.y, m2-exp.y (yyrule, yyname, yyss, yyssp, yyvs, yyvsp):
	Remove defines to remap non-yacc symbols, thus backing out of
	previous recent changes.  Standard policy is that non-yacc parser
	generators get fixed, rather than adding bug workarounds in gdb
	for each new one that pops up.  Expand comment to note this.
	* c-exp.y, m2-exp.y (YYDEBUG):  Revert back to disabled by default.