Update utils.c

Fix error IP_ORIGDSTADDR undefined
utils.c: In function 'red_recv_udp_pkt':
utils.c:58:24: error: 'IP_ORIGDSTADDR' undeclared (first use in this function)
utils.c:58:24: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [utils.o] Error 1