If sa_build_index() encounters a corrupt buffer, don't panic.
Add info to zfs ring buffer and return EIO. This allows for a cleaner
error recovery path.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Issue #6500Closes#7487