udhcpc: fix for some Android toolchain breakage

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 11f7b2d..915f659 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -29,6 +29,20 @@
 #include <linux/filter.h>
 #include <linux/if_packet.h>
 
+#ifndef PACKET_AUXDATA
+# define PACKET_AUXDATA 8
+struct tpacket_auxdata {
+	uint32_t tp_status;
+	uint32_t tp_len;
+	uint32_t tp_snaplen;
+	uint16_t tp_mac;
+	uint16_t tp_net;
+	uint16_t tp_vlan_tci;
+	uint16_t tp_padding;
+};
+#endif
+
+
 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */