Fix missing pcap_fopen_offline_with_tstamp_precision. Fixes google#611

This happened due to merging tstamp + unix/windows split.
Problem is that the #define used for checking if this is missing is
defined by the check above...

Author: notti

pcap/pcap_unix.go

@@ -69,6 +69,11 @@ pcap_t *pcap_open_offline_with_tstamp_precision(const char *fname, u_int precisi
   return pcap_open_offline(fname, errbuf);
 }
 
+pcap_t *pcap_fopen_offline_with_tstamp_precision(FILE *fp, u_int precision,
+  char *errbuf) {
+  return pcap_fopen_offline(fp, errbuf);
+}
+
 int pcap_set_tstamp_precision(pcap_t *p, int tstamp_precision) {
   if (tstamp_precision == PCAP_TSTAMP_PRECISION_MICRO)
     return 0;
@@ -161,15 +166,6 @@ int pcap_wait(pcap_t *p, int usec) {
 	return select(fd+1, &fds, NULL, NULL, NULL);
 }
 
-// libpcap version < v1.5 doesn't have timestamp precision (everything is microsecond)
-// see pcap.go for an explanation of why precision is ignored
-#ifndef PCAP_ERROR_TSTAMP_PRECISION_NOTSUP  // < v1.5
-pcap_t *pcap_fopen_offline_with_tstamp_precision(FILE *fp, u_int precision,
-  char *errbuf) {
-  return pcap_fopen_offline(fp, errbuf);
-}
-#endif  // < v1.5
-
 */
 import "C"