omit ip_select_ident for CentOS kernels

closes #503

Change-Id: I0f49fd706b08921c86f11258be79bc4b9debce8d

kernel-module/xt_RTPENGINE.c

@@ -3312,7 +3312,7 @@ static int send_proxy_packet4(struct sk_buff *skb, struct re_address *src, struc
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,1,0)
 	ip_select_ident(par->net, skb, NULL);
 #elif (LINUX_VERSION_CODE == KERNEL_VERSION(3,10,0) && RHEL_MAJOR == 7) /* CentOS 7 */
-	ip_select_ident(dev_net(skb_dst(skb)->dev), skb, NULL);
+	/* nothing */
 #elif LINUX_VERSION_CODE >= KERNEL_VERSION(3,15,10) \
 		|| (LINUX_VERSION_CODE < KERNEL_VERSION(3,15,0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3,14,17)) \
 		|| (LINUX_VERSION_CODE < KERNEL_VERSION(3,13,0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3,12,27)) \