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

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

Remove bridge(4) from the tree. if_bridge(4) is a full functional
replacement and has additional features which make it superior.

Discussed on: -arch
Reviewed by: thompsa
X-MFC-after: never (RELENG_6 as transition period)

Move to generating pccarddevs.h on the fly, both for the kernel and
the modules.

Also generate usbdevs.h automatically now, but a non-kernel file is
stopping that at the moment.

Add module directories and makefiles for ncv, nsp, stg and scsi_low
KLD modules.

Submitted-by: takawata