Change imaging library from dev-python/imaging to pillow

The imaging library in chroot will be changed to pillow soon and we have
to always from PIL.

BUG=chromium:398786
TEST=emerge-eve chromeos-bmpblk

Change-Id: I0bef65374f3b01a1a37804ed34c9ef2620eaaaa3
Reviewed-on: https://chromium-review.googlesource.com/1226571
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed