It used to be module-relative, but since we switched to decoding
sections individually, the offsets would be section-relative.
This CL fixes this by adding the buffer offset to the reported
locations.

R=ahaas@chromium.org

Change-Id: I27240832e5cbd625d6b952678503252017dd83f3
Reviewed-on: https://chromium-review.googlesource.com/568488
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46623}