Fix fluentd-gcp image config by avoiding processing its own logs

cluster/addons/fluentd-gcp/fluentd-gcp-image/fluent.conf

@@ -39,6 +39,13 @@
 # the name of the Kubernetes container regardless of how many times the
 # Kubernetes pod has been restarted (resulting in a several Docker container IDs).
 
+# Prevent fluentd from handling records containing its own logs. Otherwise
+# it can lead to an infinite loop, when error in sending one message generates
+# another message which also fails to be sent and so on.
+<match fluent.**>
+  type null
+</match>
+
 # Example:
 # {"log":"[info:2016-02-16T16:04:05.930-08:00] Some log text here\n","stream":"stdout","time":"2016-02-17T00:04:05.931087621Z"}
 <source>