sock api: allow to start client with no rx_thread

Change-Id: Ia30ff1e62304e65f27497ce05f8e40631c06d69e
Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
diff --git a/src/tests/vnet/session/tcp_echo.c b/src/tests/vnet/session/tcp_echo.c
index 58e29bd..bd05345 100644
--- a/src/tests/vnet/session/tcp_echo.c
+++ b/src/tests/vnet/session/tcp_echo.c
@@ -482,7 +482,7 @@
 	  return -1;
 	}
 
-      if (vl_socket_client_init_shm (0))
+      if (vl_socket_client_init_shm (0, 1 /* want_pthread */ ))
 	{
 	  clib_warning ("init shm api failed");
 	  return -1;