[db_update] Fixed bug where script would return too soon during database update

src/db_update

@@ -26,6 +26,6 @@ db_update() {
         if [[ -z $(awk -v imageid="${IMAGEID}" -v trackid="${trackid}" 'BEGIN{FS="\t"}{if($2==imageid && $3==trackid){print $0}}' ${DB_FILE}) ]]; then
             echo -e "true\t${IMAGEID}\t${trackid}\tnull" >> ${DB_FILE}
         fi
-        return 0
     done
+    return 0
 }