Allow zfs-tests to recover from hibernation

Allow zfs-tests to recover from hibernation

When a system sleeps during a zfs-test, the time spent
hibernating is counted against the test's runtime even
though the test can't and isn't running.
This patch tries to detect timeouts due to hibernation and
reruns tests that timed out due to system sleeping.
In this version of the patch, the existing behavior of returning
non-zero when a test was killed is preserved. With this patch applied
we still return nonzero and we also automatically rerun the test we
suspect of being killed due to system hibernation.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Alek Pinchuk <apinchuk@datto.com>
Closes #8575