netfilter: nf_conntrack: restore nf_conntrack_htable_size as exported symbol

This is required to iterate over the hash table in cttimeout, ctnetlink
and nf_conntrack_ipv4.

>> ERROR: "nf_conntrack_htable_size" [net/netfilter/nfnetlink_cttimeout.ko] undefined!
   ERROR: "nf_conntrack_htable_size" [net/netfilter/nf_conntrack_netlink.ko] undefined!
   ERROR: "nf_conntrack_htable_size" [net/ipv4/netfilter/nf_conntrack_ipv4.ko] undefined!

Fixes: adf0516845bcd0 ("netfilter: remove ip_conntrack* sysctl compat code")
Reported-by: kbuild test robot <[email protected]>
Reported-by: Stephen Rothwell <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
1 file changed