Also sort all variants in configuration mapping.

Bug: v8:7285
Change-Id: I2d3032b911e48c34557e47e50345fb29da7bbe85
Reviewed-on: https://chromium-review.googlesource.com/866502Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50584}