MFV r251623:

zpool create should treat -O mountpoint and -m the same

Illumos ZFS issues:
  3745 zpool create should treat -O mountpoint and -m the same

MFC after:      2 weeks
MFV r251624:

txg commit callbacks don't work

Illumos ZFS issues:
  3747 txg commit callbacks don't work

MFC after:      2 weeks
MFV r251626:

ZFS event processing should work on R/O root filesystems

Illumos ZFS issues:
  3749 zfs event processing should work on R/O root filesystems

MFC after:      2 weeks
Borrow the algorithm from kvm_getprocs() to fix procstat_getprocs() to
handle the case where the process tables grows in between the calls to
fetch the size and fetch the table.

MFC after:	1 week