Trying to append nfacct related rules results in an unhelpful message.
Although it is suggested to look for more information in dmesg, nothing
can be found there.
# iptables -A <chain> -m nfacct --nfacct-name <acct-object>
iptables: Invalid argument. Run `dmesg' for more information.
This patch fixes the memory misalignment by enforcing 8-byte alignment
within the struct's first revision. This solution is often used in many
other uapi netfilter headers.