Illumos 5438 - zfs_blkptr_verify should continue after zfs_panic_recover

5438 zfs_blkptr_verify should continue after zfs_panic_recover
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Xin LI <delphij@freebsd.org>
Approved by: Dan McDonald <danmcd@omniti.com>

References:

https://www.illumos.org/issues/5438
https://github.com/illumos/illumos-gate/commit/5897eb4

Ported-by: kernelOfTruth kerneloftruth@gmail.com
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>