Strangely, the file seems to be truncated after its commit on cvs.tcpdump.org. This update should fix the problem.

pcap-stdinc.h

@@ -18,6 +18,7 @@
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
+#ifdef WIN32
 
 #define SIZEOF_CHAR 1
 #define SIZEOF_SHORT 2
@@ -41,4 +42,22 @@
 #define vsnprintf _vsnprintf
 #define inline __inline 
 
+#else
+
+#include <unistd.h>
+#include <netdb.h>
+#include <sys/socket.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/timeb.h>
+#include <sys/file.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#ifdef HAVE_SYS_SOCKIO_H
+#include <sys/sockio.h>
+#include <arpa/inet.h>
+#endif
+
 #endif