chore: initial import from KNEL/PFVCluster@041d311 [#769]

Split per O&M lane work order. Full history: KNEL/PFVCluster.
shellcheck debt fixed in librenms-agent (quoting, arithmetic, backticks);
fixes upstream ntp-server.sh bug: input_wakeups reported PACKETSENDFAILURES
instead of INPUTWAKEUPS. mysql.sh (PHP-in-.sh) exempt per house rule.

https://projects.knownelement.com/issues/769#note-4152

librenms-agent/agent/postfix-queues

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+#Written by Valec 2006. Steal and share.
+#Get postfix queue lengths
+
+#extend mailq /opt/observer/scripts/getmailq.sh
+
+QUEUES="incoming active deferred hold"
+
+for i in $QUEUES; do
+        COUNT=$(qshape "$i" | grep TOTAL | awk '{print $2}')
+        printf "$COUNT\n"
+done