Make 502.pfdenied find blacklistd/* filter names dynamically

This change is needed to make the 520.pfdenied script find the new
blacklistd/* anchor points for reporting blocked traffic.

Reviewed by:	kp
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation

etc/periodic/security/520.pfdenied

@@ -44,8 +44,7 @@ rc=0
 if check_yesno_period security_status_pfdenied_enable
 then
 	TMP=`mktemp -t security`
-	touch ${TMP}
-	for _a in "" blacklistd
+	for _a in "" $(pfctl -a "blacklistd" -sA 2>/dev/null)
 	do
 		pfctl -a ${_a} -sr -v -z 2>/dev/null | \
 		nawk '{if (/^block/) {buf=$0; getline; gsub(" +"," ",$0); if ($5 > 0) print buf$0;} }' >> ${TMP}