Make arm64 test script comaptable with old versions of gsutil.

NOTRY=true
R=borenet@google.com

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/183883020

git-svn-id: http://skia.googlecode.com/svn/trunk@13668 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed