periodic: Fix backwards compatibility for daily_status_security_* vars.

Most daily_status_security_* variables in periodic.conf were changed to
security_status_* in SVN r254974. The compatibility code for the old names
did not work.

PR:		204331
Submitted by:	martin at lispworks.com
MFC after:	1 week

etc/defaults/periodic.conf

@@ -311,8 +311,8 @@ if [ -z "${source_periodic_confs_defined}" ]; then
 		    "use \$$var instead." >&2
 		case "$value" in
 		[Yy][Ee][Ss])
-			$var=YES
-			$periodvar=daily
+			eval $var=YES
+			eval $periodvar=daily
 			;;
 		*)
 			eval $var=\"$value\"