Simplify diff exit code handling.
Summary:
This fixes T9970 in an alternate manner, with the same effect: the
binary_safe_diff.sh script returns 0 if the diff succeeds, 1 in all
other cases.
Test Plan:
Tested locally with a fixed binary_safe_diff.sh, resulting in this
correct review:
https://reviews.freebsd.org/D4542
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley, Blessed Reviewers
Subscribers: eadler, Korvin, stevenh
Maniphest Tasks: T9970
Differential Revision: https://secure.phabricator.com/D14759