Fix compile warnings using gcc 4.3.2

libxt_dccp.c: In function 'port_to_service':
libxt_dccp.c:196: warning: implicit declaration of function 'htons'
libxt_sctp.c: In function 'port_to_service':
libxt_sctp.c:321: warning: implicit declaration of function 'htons'
libxt_tcp.c: In function 'port_to_service':
libxt_tcp.c:220: warning: implicit declaration of function 'htons'
libxt_udp.c: In function 'port_to_service':
libxt_udp.c:104: warning: implicit declaration of function 'htons'

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/extensions/libxt_sctp.c b/extensions/libxt_sctp.c
index 4f1d13f..5bd06a3 100644
--- a/extensions/libxt_sctp.c
+++ b/extensions/libxt_sctp.c
@@ -14,6 +14,7 @@
 #include <netdb.h>
 #include <ctype.h>
 
+#include <netinet/in.h>
 #include <xtables.h>
 
 #ifndef ARRAY_SIZE