* scripts/abilist.awk: If given -v filename_regexp and/or -v

* scripts/abilist.awk: If given -v filename_regexp and/or -v

	libname_regexp when parsing names, then produce output only
	for those matching the given regexps.  In combine mode, save all
	stanzas for a final sorting by stanza header at the end.
	Emit a blank line between stanzas.