Actually handle mount options; readonly, xattr, atime, noexec, nosetuid.
Properly close (also do not take) z_mtime_vp when in readonly, so that
unmount will work.
Take out Linux unmount/remount calls for setting VFS options, darwin lets
you change them dynamically.

Still missing is taking mount arguments, ie, "mount -o ro" and
"import -o readonly". They are currently ignored.
Fixes xattr=on reversed mapping to MNT_NOUSERXATTR.

xattr=on should map to clearing MNT_NOUSERXATTR.
xattr=off should map to setting MNT_NOUSERXATTR.

This fix is from Lundman.
Change userland mount option from string, to build "int flags". This now
handles the most common mount options.

Extended mount to use flags, and pass flags to kernel.

Add two additional dataset properties "finderbrowse" and "ignoreowner" for
APPLE platform. Consider using "com.apple.browse" style property names though.
Remove compile flag "always-no-unused-but-set-variable" as it fails on
10.6 build
The original MacZFS code keeps "com.apple.system.mtime" vp reference the
entire mount time, but this is causing issues at export time, often requiring
forced export. We should re-work this, and find out why it was required in
the first place.
If hostid is not set, use IOReg to fetch hardware uuid and generate one (from
ilovezfs example).
Rename new Apple props
Remove legacy MacZFS logic
Allow libzfs to mount snapshots, as a temporary solution to snapshots.
Merge branch 'master' into ctldir

Conflicts:
	lib/libzfs/libzfs_mount.c
WIP: Allow 'zfs mount' and 'zfs umount' to also handle snapshot mounts
temporarily, allowing for the use of snapshots. Currently forced to
/mnt as the .zfs/snapshot dir needs more work. (panics)