- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

fix fat-fingering in r253996

MFC after: 17 days
X-MFC with: r253996

opensolaris code: translate INVARIANTS to DEBUG and ZFS_DEBUG

Do this by forcing inclusion of
sys/cddl/compat/opensolaris/sys/debug_compat.h
via -include option into all source files from OpenSolaris.
Note that this -include option must always be after -include opt_global.h.

Additionally, remove forced definition of DEBUG for some modules and fix
their build without DEBUG.

Also, meaning of DEBUG was overloaded to enable WITNESS support for some
OpenSolaris (primarily ZFS) locks. Now this overloading is removed and
that use of DEBUG is replaced with a new option OPENSOLARIS_WITNESS.

MFC after: 17 days

Jusy use i386 version of cyclic_machdep.c on all supported architectures.
It's generic enough to cover all of them.

MFtbemd:

Use MACHINE_CPUARCH in preference to MACHINE_ARCH. The former is the
source code location of the machine, the latter the binary output. In
general, we want to use MACHINE_CPUARCH instead of MACHINE_ARCH unless
we're tesitng for a specific target. The isn't even moot for
i386/amd64 where there's momemntum towards a MACHINE_CPUARCH == x86,
although a specific cleanup for that likely would be needed...

The amd64 version of the cyclic dtrace module is a verbatim copy of the
i386 version, so instead having a copy of the same file, use Makefile
foo to include the i386 version on amd64.

The cyclic code is in sys/cddl/dev/cyclic to be consistent with
the other stuff.

Add the DTrace kernel module makefiles.