Fixing Issue #4641 - Save total snmp_ports into settings table for spine

This change, when combined with a to be committed spine change will help improve performance of spine on very busy systems where the default snmp port is the only one in use.

CHANGELOG

@@ -113,6 +113,7 @@ Cacti CHANGELOG
 -feature#4631: Additional choices for Heartbeat when creating a Data Source Profile
 -feature#4636: jQueryMulti-select 3.0.1 includes i18n upgrade to it
 -feature#4637: Have Cacti's MultiSelect CheckAll and UnCheckAll use Font-Awesome 
+-feature#4641: Improve spine performance by storing the total number of system snmp_ports in use
 
 1.2.19
 -security#4356: Further fixes for grave character security protection

poller.php

@@ -261,7 +261,18 @@ function sig_handler($signo) {
 	}
 }
 
-/* determine the number of active profiles to improve poller performance
+/**
+ * shortcut some expensive logic in spine if possible the
+ * order by snmp port is a rare thing to be needed and only
+ * needs to occur if your are talking to more than one snmp
+ * agent on a host.
+ */
+$total_ports = db_fetch_cell('SELECT COUNT(DISTINCT snmp_port)
+	FROM poller_item');
+set_config_option('total_snmp_ports', $total_ports);
+
+/**
+ * determine the number of active profiles to improve poller performance
  * under some circumstances.  Save this data for spine and cmd.php.
  */
 $active_profiles = db_fetch_cell('SELECT COUNT(DISTINCT data_source_profile_id)