3877 fast reboot does not work with extended partition
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Reviewed by: Hans Rosenfeld <hans.rosenfeld@nexenta.com>
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
	[illumos-gate merge]

commit 01f9868a8d2cedd96c3aeefbd7233aa77f7b72ff
    3877 fast reboot does not work with extended partition