has been broken at least since 4.4Lite moved most of the #defines out of
<sys/ioctl.h>. This should be done better. Only a few headers are
searched.
Added some #includes so that ioctl.c compiles. The networking headers
have a maze of undocumented interdependencies and ioctl.c now actually
supports networking ioctls.
and then also add a declaration of ernno as an extern int, because we
lose that due to having KERNEL defined while we include errno.h.
Reviewed by: Geoff.
