linux(4): Rename struct l_ifreq members names to avoid conflicts with FreeBSD

[dchagin]

Summary

For now we are using mixed names to access struct ifreq members, some
of Linux (ifr_name, ifr_ifindex), others of FreeBSD. To avoid conflicts
switch to use FreeBSD names.

Reported by: jhibbits

[jhibbits]

Thanks!

[melifaro]

sys/compat/linux/linux_socket.h

342

I'd explicitly add Static_assert() conditions on each of the fields in linux_something.c.
People don't read notes but have to read compiler errors :-)

[dchagin]

assert most important names of the struct ifreq members are equal to native ifreq