[developer] [openzfs/openzfs] Merge remote-tracking branch 'illumos/master' into illumos-sync (#555)

You can view, comment on, or merge this pull request online at: https://github.com/openzfs/openzfs/pull/555 -- Commit Summary -- * 8792 mac_tx_srs_quiesce() can kill a maxbw link * 8652 Tautological comparisons with ZPROP_INVAL (followup) * 8760 troff: variable 'type' set but not used

[developer] [openzfs/openzfs] 9125 mdb's ::zfs_params needs updating (#554)

Running `::zfs_params` on a semi-recent Illumos build (8a051e3a96) produces the following warning: ``` mdb: variable zfetch_block_cap not found: unknown symbol name ``` Full output: ``` loli@openindiana:~$ uname -a SunOS openindiana 5.11 master-0-g8a051e3a96 i86pc i386 i86pc loli@openindiana:~$