click/icmp: bail out on OOM

Change-Id: Ia7b9f3c4a4e7547d17251edac67c75f967507b3f
Reviewed-on: https://gerrit.ikarem.io/74139
Static-Analysis: Jenkins Build System <jenkins@meraki.com>
Tested-by: Jenkins Build System <jenkins@meraki.com>
Reviewed-by: Peter Hurley <peter@meraki.com>
Signed-off-by: Derrick Pallas <pallas@meraki.com>

elements/icmp/icmpsendpings.cc

@@ -154,7 +154,7 @@ ICMPPingSource::make_packet(WritablePacket *q)
     q->set_ip_header(nip, sizeof(click_ip));
     q->timestamp_anno().assign_now();
 
-    if (_receiver)
+    if (p && _receiver)
 	_receiver->send_timestamp[icp->icmp_sequence] = q->timestamp_anno();
 
     return q;