- 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

MFV r254750:

Add support of Illumos dumps on zvol over RAID-Z.

Note that this only adds the features. FreeBSD would
still need more work to support dumping on zvols.

Illumos ZFS issues:
2932 support crash dumps to raidz, etc. pools

MFC after: 1 month
Approved by: re (ZFS blanket)

MFV r245512:

* Illumos zfs issue #3035 [1] LZ4 compression support in ZFS.

LZ4 is a new high-speed BSD-licensed compression algorithm created
by Yann Collet that delivers very high compression and decompression
performance compared to lzjb (>50% faster on compression, >80% faster
on decompression and around 3x faster on compression of incompressible
data), while giving better compression ratio [1].

This version of LZ4 corresponds to upstream's [2] revision 85.

Please note that for obvious reasons this is not backward read
compatible. This means once a pool have LZ4 compressed data, these
data can no longer be read by older ZFS implementations.

Local changes:

- On-stack hash table disabled and using kernel slab allocator
instead, at this time. This requires larger kernel thread stack
for zio workers. This may change in the future should we adjusted
the zio workers' thread stack size.
- likely and unlikely will be undefined if they are already defined,
this is required for i386 XEN build.
- Removed De Bruijn sequence based __builtin_ctz family of builtins
in favor of the latter. Both GCC and clang supports these builtins.
- Changed the way the LZ4 code detects endianness.
- Manual pages modifications to mention the feature based on Illumos
counterpart.
- Boot loader changes to make it support LZ4 decompression.

[1] https://www.illumos.org/issues/3035
[2] http://code.google.com/p/lz4/source/list

Obtained from: Illumos (13921:9d721847e469)
Tested on: FreeBSD/amd64
MFC after: 1 month

Merge recent vendor changes:
3100 zvol rename fails with EBUSY when dirty
3104 eliminate empty bpobjs
3120 zinject hangs in zfsdev_ioctl() due to uninitialized zc

References:
https://www.illumos.org/issues/3100
https://www.illumos.org/issues/3104
https://www.illumos.org/issues/3120

Obtained from: illumos (vendor/illumos, vendor/illumos-sys)
MFC after: 2 weeks

Introduce "feature flags" for ZFS pools (bump SPA version to 5000).
Add first feature "com.delphix:async_destroy" (asynchronous destroy
of ZFS datasets).
Implement features support in ZFS boot code.

Illumos revisions merged:
13700:2889e2596bd6
13701:1949b688d5fb
2619 asynchronous destruction of ZFS file systems
2747 SPA versioning with zfs feature flags

References:
https://www.illumos.org/issues/2619
https://www.illumos.org/issues/2747

Obtained from: illumos (issue #2619, #2747)
MFC after: 1 month