When CONFIG_NF_CONNTRACK_SECMARK is not set we accidentally attempt to use
the secmark fielf of struct nf_conn.  Problem is when that config isn't set
the field doesn't exist.  whoops.  Wrap the incorrect usage in the config.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>