Added support for the 'zfs list -t snap' and 'zfs snap' aliases which are
available under Oracle Solaris 11.

This includes an update to the ZFS(8) man page to reflect all the
available alias (snap, umount, and recv).

Initial changes obtained from ZFS On Linux + fixes for man page and cmd
help:
https://github.com/zfsonlinux/zfs/commit/10b75496bb0cb7a7b8146c263164adc37f1d176a
https://github.com/zfsonlinux/zfs/commit/cf81b00a73fe47fdb21586ac1cc179b734540973

Obtained from:	https://github.com/zfsonlinux/zfs
MFC after:	2 weeks
Sponsored by:	Multiplay
Export the block size capability to guests.
- Use #defines for capability bits
- Export the VTBLK_F_BLK_SIZE capability
- Fix bug in calculating capacity: it is in
  512-byte units, not the underlying sector size

This allows virtio-blk to have backing devices
with non 512-byte sector sizes e.g. /dev/cd0, and
4K-block harddrives.

Reviewed by:	neel
MFC after:	3 days
sbin/geom/class/part/geom_part.c
	Always validate the return of find_geomcfg().  It could be NULL, for
	example when the geom is withering.

Approved by:	ken (mentor)
Sponsored by:	Spectra Logic Corporation
MFC after:	3 weeks
Update driver to version 10.0.664.0.

Many thanks to Emulex for their continued support of FreeBSD.

Submitted by:	Venkata Duvvuru <VenkatKumar.Duvvuru Emulex Com>
MFC after:	3 day