[Courgette] Make Courgette-dis trim labels.
[Courgette] Make Courgette-dis trim labels.

Courgette-gen and Courgette-apply both call TrimLabels() for the
assembly programs generated from input image. The testing mode
Courgette-dis should also do so.

Review URL: https://codereview.chromium.org/1600953002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#370052}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk