Autotest for netpacket/packet.h, as it is not available on all Linux versions.
Depend AF_PACKET on HAVE_NETPACKET_PACKET_H.
diff --git a/configure b/configure
index dda7659..017e3fb 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# From configure.in Revision: 1.242 
+# From configure.in Revision: 1.243 
 
 # Guess values for system-dependent variables and create Makefiles.
 # Generated automatically using autoconf version 2.13 
@@ -1886,7 +1886,7 @@
 sys/audioio.h sys/file.h sys/lock.h sys/modem.h db_185.h db.h \
 sys/param.h sys/poll.h sys/select.h sys/socket.h sys/time.h sys/times.h \
 sys/un.h sys/utsname.h sys/wait.h pty.h libutil.h \
-ndbm.h db1/ndbm.h gdbm/ndbm.h sys/resource.h
+ndbm.h db1/ndbm.h gdbm/ndbm.h sys/resource.h netpacket/packet.h
 do
 ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6