GitLab

This CL fixes:
* Parsing the release file to obtain the desired SHA256 sum when there
  are multiple hash algorithms listed in different orders.
* Removes a list of directories to relativize symlinks and replaces it
  with a direct check on the directory nesting.

BUG=751812
R=thestig@chromium.org

Change-Id: If3692f0633ba7ad059ab3c7d0945f4b7ef11786e
Reviewed-on: https://chromium-review.googlesource.com/598931Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491506}