Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add new TAPGIFNAME tap(4) character device ioctl. This is a
convenient shortcut to obtain network interface name using
file descriptor for character device.

Obtained from: NetBSD
MFC after: 1 week

Fix our ioctl(2) implementation when the argument is "int". New
ioctls passing integer arguments should use the _IOWINT() macro.
This fixes a lot of ioctl's not working on sparc64, most notable
being keyboard/syscons ioctls.

Full ABI compatibility is provided, with the bonus of fixing the
handling of old ioctls on sparc64.

Reviewed by: bde (with contributions)
Tested by: emax, marius
MFC after: 1 week

/* -> /*- for license, minor formatting changes

Add the tap driver.

The tap driver is used to present a virtual Ethernet interface to the
system. Packets presented by the network stack to the interface are
made available to a character device in /dev. With tap and the bridge
code, you can make remote bridge configurations where both sides of
the bridge are separated by userland daemons.

This driver also has a special naming hack to allow it to serve a similar
purpose to the vmware port.

Submitted by: myevmenkin@att.com, vsilyaev@mindspring.com