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

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

Let modules use the kernel's opt_*.h files if built along with
the kernel by wrapping all targets for fake opt_*.h files in
.if defined(KERNBUILDDIR). Thus, such fake files won't be
created at all if modules are built with the kernel.

Some modules undergo cleanup like removing unused or unneeded
options or .h files, without which they wouldn't build this way
or the other.

Reviewed by: ru
Tested by: no binary changes in modules built alone
Tested on: i386 sparc64 amd64

Fix module build by adding options to Makefile.

Drop <bsd.man.mk> support from <bsd.kmod.mk>.

Not objected to by: -current

Use a consistent style and one much closer to the rest of /usr/src

When manual pages are moved or removed, MANX should be changed
to NOMAN.

Reported by: bde

Move the netgraph-related manual pages into share/man/man4/, as
discussed with archie.

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

Move netgraph node type man pages from section 8 to section 4.

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.

Zap KMODDEPS line

- Document updates in iface netgraph node type functionality
- Remove makefile hacks for opt_inet.h, etc: the KLD now supports
whatever address families your kernel was compiled with automagically

Revert previous checkin; I incorrectly thought that it was needed
due to having an old version of bsd.kmod.mk.

Caught by: bde

Fix 'make clean'

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}).

bpf need no longer be an option

Whistle's Netgraph link-layer (sometimes more) networking infrastructure.
Been in production for 3 years now. Gives Instant Frame relay to if_sr
and if_ar drivers, and PPPOE support soon. See:
ftp://ftp.whistle.com/pub/archie/netgraph/index.html
for on-line manual pages.

Reviewed by: Doug Rabson (dfr@freebsd.org)
Obtained from: Whistle CVS tree