bsd's ifconf conflicts with osv's; rename it.

We use the bsd version in <osv/ioctl.h>, since we currently don't support
the Linux-ABI variants of these ioctls.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Tested-By: Benoit Canet <benoit@irqsave.net>