Don't call ip_addr_isany() on objects which can't be NULL.

GCC will issue a warning when the ip_addr_isany() macro is used on
a pointer which can never be NULL since the macros NULL check will
always be false:
    #define ip_addr_isany(addr1) ((addr1) == NULL || \
                                  (addr1)->addr == IPADDR_ANY)

In these cases, it is probably clearer to just perform the
x.addr == IPADDR_ANY check inline.

Author: adamgreen

libraries/net/lwip/lwip/core/ipv4/ip.c

@@ -400,7 +400,7 @@ ip_input(struct pbuf *p, struct netif *inp)
   /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
   /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
-  if (check_ip_src && !ip_addr_isany(&current_iphdr_src))
+  if (check_ip_src && current_iphdr_src.addr != IPADDR_ANY)
 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
   {  if ((ip_addr_isbroadcast(&current_iphdr_src, inp)) ||
          (ip_addr_ismulticast(&current_iphdr_src))) {