netfilter: xtables: add struct xt_mtdtor_param::net

Add ->net to match destructor list like ->net in constructor list.

Make sure it's set in ebtables/iptables/ip6tables, this requires to
propagate netns up to *_unregister_table().

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

include/linux/netfilter/x_tables.h

@@ -216,6 +216,7 @@ struct xt_mtchk_param {
 
 /* Match destructor parameters */
 struct xt_mtdtor_param {
+	struct net *net;
 	const struct xt_match *match;
 	void *matchinfo;
 	u_int8_t family;