ldlex.l tidy

Underscore was specified twice in all these patterns, and backslash
twice in some.  Flex warned about the $SYSROOT rule, which is covered
by earlier rules:  "ldlex.l:386: warning, rule cannot be matched".

	* ldlex.l: Formatting.
	(CMDFILENAMECHAR, CMDFILENAMECHAR1): Delete.
	(FILENAMECHAR1, SYMBOLNAMECHAR1, FILENAMECHAR, WILDCHAR),
	(NOCFILENAMECHAR): Remove duplicate chars.  Reorder.
	(SYMBOLCHARN): Likewise.  Rename to SYMBOLNAMECHAR.
	(<INPUTLIST>"$SYSROOT"..): Delete rule.