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

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

Update to build both bktr and bktr_mem modules

Avoid the modules madness I inadvertently introduced by making the
cloning infrastructure standard in kern_conf. Modules are now
the same with or without devfs support.

If you need to detect if devfs is present, in modules or elsewhere,
check the integer variable "devfs_present".

This happily removes an ugly hack from kern/vfs_conf.c.

This forces a rename of the eventhandler and the standard clone
helper function.

Include <sys/eventhandler.h> in <sys/conf.h>: it's a helper #include
like <sys/queue.h>

Remove all #includes of opt_devfs.h they no longer matter.

Use .include <bsd.kmod.mk> to get to ../../*/conf/kmod.mk instead of
encoding the relative path.

Pull in sys/conf/kmod.mk, rather than /usr/share/mk/bsd.kmod.mk.
This means that the kernel can be totally self contained now and is not
dependent on the last buildworld to update /usr/share/mk. This might
also make it easier to build 5.x kernels on 4.0 boxes etc, assuming
gensetdefs and config(8) are updated.

Removed special rules for building and cleaning device interface files
and empty options files. The rules are now generated automatically in
bsd.kmod.mk. Cleaned up related things ($S and ${CLEANFILES}).

Add vnode_if.c to CLEANFILES.

Make the bktr module build. The Makefile was badly mangled, including
leaving the ".c" out of most of the SRCS= source files.

Update to use new Bt848 driver

Use new location of Bt848 driver.
Remove NPCI generation as the driver no longer checks for NPIC > 0

add vnode_if.h

$Id$ -> $FreeBSD$

Change perl5 to perl (same change as made in the fxp module)

Makefile to build a loadable bktr Bt848/Bt878 device driver
This allows the bt848 grabber to be loaded in the boot loader or
after bootup without the need for a custom kernel