Only accept the hermetic toolchain license if newer.
Only accept the hermetic toolchain license if newer.

Accepting an older license will break newer toolchains.  Check if a bot's
last agreed to toolchain is newer.  If it's older, accept the hermetic toolchain.

BUG=

Review-Url: https://codereview.chromium.org/1956073003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#392356}

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