pflogd: Define structures removed in libpcap-1.10.5

In libpcap-1.10.5, two structures that we rely on, pcap_timeval and
pcap_sf_pkthdr, were made private.

c2d8cbb977

Temporarily define them here to fix the build.  kp and I will
investigate a permanent solution at EuroBSDCon in Dublin.

Reviewed by:	kp
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D46676

contrib/pf/pflogd/pflogd.h

@@ -40,6 +40,19 @@ int	priv_open_log(void);
 int	priv_move_log(void);
 pcap_t *pcap_open_live_fd(int fd, int snaplen, char *ebuf);
 
+/* XXX TODO: Investigate a permanent solution, rather than defining these two
+   structures here. */
+struct pcap_timeval {
+	bpf_u_int32 tv_sec;	/* seconds */
+	bpf_u_int32 tv_usec;	/* microseconds */
+};
+
+struct pcap_sf_pkthdr {
+	struct pcap_timeval ts;	/* time stamp */
+	bpf_u_int32 caplen;	/* length of portion present */
+	bpf_u_int32 len;	/* length of this packet (off wire) */
+};
+
 void set_pcap_filter(void);
 /* File descriptor send/recv */
 void send_fd(int, int);