Clang update script: a few more master -> main changes

Chromium's main branch was renamed recently.

Bug: none
Change-Id: Ia5ac606ca8189ba14396785d86052cd7e6fa67da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2825440
Commit-Queue: Hans Wennborg <hans@chromium.org>
Commit-Queue: Reid Kleckner <rnk@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Reviewed-by: Reid Kleckner <rnk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#872560}
GitOrigin-RevId: a154a5ae560b64c3df715b943060814450db519c
2 files changed