netfilter: export xt_HMARK.h to userland

This file contains the API for the target "HMARK", hence it should be exported
to userland.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/Kbuild

@@ -22,6 +22,7 @@ header-y += xt_CONNMARK.h
 header-y += xt_CONNSECMARK.h
 header-y += xt_CT.h
 header-y += xt_DSCP.h
+header-y += xt_HMARK.h
 header-y += xt_IDLETIMER.h
 header-y += xt_LED.h
 header-y += xt_LOG.h