MFC r324346: MFV r316931: 6268 zfs diff confused by moving a file to another directory

MFC r305209: MFV r302660: 6314 buffer overflow in dsl_dataset_name

illumos/illumos-gate@9adfa60d484ce2435f5af77cc99dcd4e692b6660
https://github.com/illumos/illumos-gate/commit/9adfa60d484ce2435f5af77cc99dcd4e6
92b6660

https://www.illumos.org/issues/6314
Callers of dsl_dataset_name pass a buffer of size ZFS_MAXNAMELEN, but
dsl_dataset_name copies the datasets' name PLUS the snapshot name to it,
resulting in a max of 2 * ZFS_MAXNAMELEN + '@'.

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

MFC r305207: MFV r302659: 6931 lib/libzfs: cleanup gcc warnings

illumos/illumos-gate@88f61dee20b358671b1b643e9d1dbf220a1d69be
https://github.com/illumos/illumos-gate/commit/88f61dee20b358671b1b643e9d1dbf220a1d69be

https://www.illumos.org/issues/6931
need cleanup:
CERRWARN += -_gcc=-Wno-switch
CERRWARN += -_gcc=-Wno-parentheses
CERRWARN += -_gcc=-Wno-unused-function

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Igor Kozhukhov <ikozhukhov@gmail.com>

MFC r296541: MFV r296540: 4448 zfs diff misprints unicode characters

Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: Toomas Soome <tsoome@me.com>
Approved by: Matthew Ahrens <mahrens@delphix.com>
Author: Joshua M. Clulow <jmc@joyent.com>

illumos/illumos-gate@b211eb9181f99c20acbf4c528f94cb44b4ca8c31

MFC r277300 (by smh): Mechanically convert cddl sun #ifdef's to illumos

Since the upstream for cddl code is now illumos not sun, mechanically
convert all sun #ifdef's to illumos #ifdef's which have been used in all
newer code for some time.

Also do a manual pass to correct the use if #ifdef comments as per style(9)
as well as few uses of #if defined(__FreeBSD__) vs #ifndef illumos.

MFC r289531: 5847 libzfs_diff should check zfs_prop_get() return

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Albert Lee <trisk@omniti.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Alexander Eremin <a.eremin@nexenta.com>

illumos/illumos-gate@8430278980a48338e04c7dd52b495b7f1551367a

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

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

Properly print characters larger than 127.

Submitted by: noordsij <noordsij@cs.helsinki.fi>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
MFC after: 1 month

Finally... Import the latest open-source ZFS version - (SPA) 28.

Few new things available from now on:

- Data deduplication.
- Triple parity RAIDZ (RAIDZ3).
- zfs diff.
- zpool split.
- Snapshot holds.
- zpool import -F. Allows to rewind corrupted pool to earlier
transaction group.
- Possibility to import pool in read-only mode.

MFC after: 1 month