udp: fix for multiple workers and add test

Since the main thread is not used for session polling anymore, when vpp
is started with multiple wokers, allocate connections on the first. Also
add a simple udp make test.

Change-Id: Id869f5d89e0fced51048f0384fa86a5022258b7c
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/session/transport.c b/src/vnet/session/transport.c
index b3d42d0..a401190 100644
--- a/src/vnet/session/transport.c
+++ b/src/vnet/session/transport.c
@@ -207,6 +207,12 @@
   return tp_vfts[tp].tx_type;
 }
 
+u8
+transport_protocol_is_cl (transport_proto_t tp)
+{
+  return (tp_vfts[tp].service_type == TRANSPORT_SERVICE_CL);
+}
+
 #define PORT_MASK ((1 << 16)- 1)
 
 void