Merge remote-tracking branch 'illumos-ml/master' into titanic

Some zev merge conflicts fixed.

Conflicts:
usr/src/uts/common/fs/zfs/zfs_ioctl.c
usr/src/uts/common/fs/zfs/zvol.c

3975 ddi_periodic_add(9F) is entirely rubbish
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Approved by: Dan McDonald <danmcd@nexenta.com>