netfilter: xtables: CONFIG_COMPAT redux

Ifdef out
	struct nf_sockopt_ops::compat_set
	struct nf_sockopt_ops::compat_get
	struct xt_match::compat_from_user
	struct xt_match::compat_to_user
	struct xt_match::compatsize
to make structures smaller on COMPAT=n kernels.

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