supersize: Tweak diff symbol matching for generated symbols

E.g. CSWTCH.61 and CSWTCH.62 will now match as long as they are in the
same object file.

BUG=708865,717550

Review-Url: https://codereview.chromium.org/2857153002
Cr-Commit-Position: refs/heads/master@{#469045}
3 files changed