freebsd and linux have a different "struct sockaddr".
In ff_recvmsg and ff_recvmsg, ```msg->msg_name```,which can refer to address, can be expected to be converted .
ipfw -- interface for firewall, packet scheduler, NAT and so on.
It is comprised of several components: the kernel firewall filter rule processor and its integrated packet accounting facility, the logging facility, NAT, a forward facility, a bridge facility, and an ipstealth facility.
Note that the `dummynet` traffic shaper is not merged.
Since f-stack run with polling mode, nginx will call gettimeofday every loop, and cost a lot.
With this commit, f-stack will update current timespec periodically in
ff_hardclock_job. And ff_gettimeofday will get this value.
In nginx, hijack gettimeofday to call ff_gettimeofday.
Changes:
Remove directory `ipc`, and add a new directory `compat`.
Directory `compat` includes some FreeBSD source files to be compatible
with Linux.
Port FreeBSD ifconfig to F-Stack.