Fix "redefinition of 'bpf_program'"
https://github.com/Ettercap/ettercap/issues/326
--- include/ec.h.orig	2013-09-11 15:18:45.000000000 -0500
+++ include/ec.h	2013-12-03 10:58:14.000000000 -0600
@@ -16,6 +16,11 @@
    #include <windows.h>
 #endif
 
+#ifdef OS_DARWIN
+   #define PCAP_DONT_INCLUDE_PCAP_BPF_H 1
+   #include <net/bpf.h>
+#endif
+
 #if !defined (__USE_GNU)   /* for memmem(), strsignal(), etc etc... */
    #define __USE_GNU
 #endif