netfilter: ctnetlink: restore inlining for netlink message size calculation

netfilter: ctnetlink: restore inlining for netlink message size calculation

Calm down gcc warnings:

net/netfilter/nf_conntrack_netlink.c:529:15: warning: 'ctnetlink_proto_size' defined but not used [-Wunused-function]
 static size_t ctnetlink_proto_size(const struct nf_conn *ct)
               ^
net/netfilter/nf_conntrack_netlink.c:546:15: warning: 'ctnetlink_acct_size' defined but not used [-Wunused-function]
 static size_t ctnetlink_acct_size(const struct nf_conn *ct)
               ^
net/netfilter/nf_conntrack_netlink.c:556:12: warning: 'ctnetlink_secctx_size' defined but not used [-Wunused-function]
 static int ctnetlink_secctx_size(const struct nf_conn *ct)
            ^
net/netfilter/nf_conntrack_netlink.c:572:15: warning: 'ctnetlink_timestamp_size' defined but not used [-Wunused-function]
 static size_t ctnetlink_timestamp_size(const struct nf_conn *ct)
               ^

So gcc compiles them out when CONFIG_NF_CONNTRACK_EVENTS and
CONFIG_NETFILTER_NETLINK_GLUE_CT are not set.

Fixes: 4054ff45454a9a4 ("netfilter: ctnetlink: remove unnecessary inlining")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>