update to ZFS Boot Support (2006/370)

[Lori Alt]

One of the aspects of zfs boot support is the ability
to do a non-legacy mount of the root file system, and
any subordinate file systems in the boot environment.
Using regular zfs mounts instead of legacy mounts
for root requires two changes, one of which is a new
interface:

1.  The new interface is the new "noauto" value for the
  "canmount" dataset property, defined by this case.

2.  Some changes are also required to the SMF start-up
 scripts (fs-root, fs-usr, and fs-local) to use zfs mounts
 instead of legacy mounts.  This does not change any
 interface.

These two changes will be integrated separately into
Solaris from the rest of the zfs boot support.  They are
being integrated as fixes to CRs 6661070 (need
canmount=noauto option for datasets to allow mount
point to be set, but no mount done) and 6664570
(need support for canmount=noauto in smf scripts).
These enhancements to zfs are necessary for Indiana
and are not dependent on any other aspects of zfs boot
support, and thus can be integrated separately.

Lori