MFV r354378,r354379,r354386: 10499 Multi-modifier protection (MMP)

10499 Multi-modifier protection (MMP)
illumos/illumos-gate@e0f1c0afa46cc84d4b1e40124032a9a87310386e
https://github.com/illumos/illumos-gate/commit/e0f1c0afa46cc84d4b1e40124032a9a87310386e
https://www.illumos.org/issues/10499

Port the following ZFS commits from ZoL to illumos.
379ca9cf2 Multi-modifier protection (MMP)
bbffb59ef Fix multihost stale cache file import
0d398b256 Do not initiate MMP writes while pool is suspended

10701 Correct lock ASSERTs in vdev_label_read/write
illumos/illumos-gate@58447f688d5e308373ab16a3b129bc0ba0fbc154
https://github.com/illumos/illumos-gate/commit/58447f688d5e308373ab16a3b129bc0ba0fbc154
https://www.illumos.org/issues/10701

Port of ZoL commit:
0091d66f4e Correct lock ASSERTs in vdev_label_read/write
At a minimum, this fixes a blown assert during an MMP test run when running on
a DEBUG build.

11770 additional mmp fixes
illumos/illumos-gate@4348eb901228d2f8fa50bb132a34248e8662074e
https://github.com/illumos/illumos-gate/commit/4348eb901228d2f8fa50bb132a34248e8662074e
https://www.illumos.org/issues/11770

Port a few additional MMP fixes from ZoL that came in after our
initial MMP port.
4ca457b065 ZTS: Fix mmp_interval failure
ca95f70dff zpool import progress kstat
(only minimal changes from above can be pulled in right now)
060f0226e6 MMP interval and fail_intervals in uberblock

Note from the committer (me).
I do not have any use for this feature and I have not tested it. I only
did smoke testing with multihost=off.
Please be aware.
I merged the code only to make future merges easier.

Portions contributed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Portions contributed by: Tim Chase <tim@chase2k.com>
Portions contributed by: sanjeevbagewadi <sanjeev.bagewadi@gmail.com>
Portions contributed by: John L. Hammond <john.hammond@intel.com>
Portions contributed by: Giuseppe Di Natale <dinatale2@llnl.gov>
Portions contributed by: Prakash Surya <surya1@llnl.gov>
Portions contributed by: Brian Behlendorf <behlendorf1@llnl.gov>
Author: Olaf Faaland <faaland1@llnl.gov>

MFC after: 4 weeks