Update gitignore for in-place build BUG=None TEST=None Change-Id: Ia0782a6643b8d252c95969afd41d701a484df551 Reviewed-on: https://chromium-review.googlesource.com/912188 Commit-Ready: Sean O'Brien <[email protected]> Tested-by: Sean O'Brien <[email protected]> Reviewed-by: Andrew de los Reyes <[email protected]>