- 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

Make dtrace_copy() actually work on PowerPC. Although unused currently,
it may be used in the future by dtrace.

Fix some ppc64 dtrace bugs, and enable systrace_freebsd32 for ppc64.

Add FBT for PowerPC DTrace. Also, clean up the DTrace assembly code,
much of which is not necessary for PowerPC.

The FBT module can likely be factored into 3 separate files: common,
intel, and powerpc, rather than duplicating most of the code between
the x86 and PowerPC flavors.

All DTrace modules for PowerPC will be MFC'd together once Fasttrap is
completed.

Fix the PowerPC DTrace copy functions. The kernel doesn't hold the same view to
the user map, so use the md copy in/out functions provided by the kernel.

MFC with: r242723

Implement DTrace for PowerPC. This includes both 32-bit and 64-bit.

There is one known issue: Some probes will display an error message along the
lines of: "Invalid address (0)"

I tested this with both a simple dtrace probe and dtruss on a few different
binaries on 32-bit. I only compiled 64-bit, did not run it, but I don't expect
problems without the modules loaded. Volunteers are welcome.

MFC after: 1 month