headers_check fix: netfilter/xt_conntrack.h

fix the following 'make headers_check' warning:

  usr/include/linux/netfilter/xt_conntrack.h:40: found __[us]{8,16,32,64} type without #include <linux/types.h>

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
diff --git a/include/linux/netfilter/xt_conntrack.h b/include/linux/netfilter/xt_conntrack.h
index f3fd83e..8f53452 100644
--- a/include/linux/netfilter/xt_conntrack.h
+++ b/include/linux/netfilter/xt_conntrack.h
@@ -5,6 +5,7 @@
 #ifndef _XT_CONNTRACK_H
 #define _XT_CONNTRACK_H
 
+#include <linux/types.h>
 #include <linux/netfilter/nf_conntrack_tuple_common.h>
 
 #define XT_CONNTRACK_STATE_BIT(ctinfo) (1 << ((ctinfo)%IP_CT_IS_REPLY+1))