MFV r301524:
7034 negative record sizes should be rejected
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Approved by: Matthew Ahrens <mahrens@delphix.com>
Author: Alex Wilson <alex.wilson@joyent.com>
illumos/illumos-gate@0b8049bfb0e291160e960697b554596289d7f0bc
MFC after: 2 weeks