quick hack to fix building following if.h split; should really have an
autoconf check for it but that's harder because AC_CHECK_HEADERS isn't enough
for this file

Index: include/common/zbxsysinc.h
--- include/common/zbxsysinc.h.orig
+++ include/common/zbxsysinc.h
@@ -305,6 +305,7 @@
 
 #ifdef HAVE_NET_IF_H
 #	include <net/if.h>
+#	include <net/if_var.h>
 #endif
 
 #ifdef HAVE_NET_IF_MIB_H