tools lib traceevent: Fix memory leakage in filter_event

It is necessary to call free_arg(arg) when add_filter_type() returns NULL
in filter_event().
Signed-off-by: Hewenliang <hewenliang4@huawei.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Link: http://lore.kernel.org/lkml/20191209063549.59941-1-hewenliang4@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/parse-filter.c

@@ -1228,8 +1228,10 @@ filter_event(struct tep_event_filter *filter, struct tep_event *event,
 	}
 
 	filter_type = add_filter_type(filter, event->id);
-	if (filter_type == NULL)
+	if (filter_type == NULL) {
+		free_arg(arg);
 		return TEP_ERRNO__MEM_ALLOC_FAILED;
+	}
 
 	if (filter_type->filter)
 		free_arg(filter_type->filter);