Adding OWNERS in /third_party/wayland

Making sure there are at least 2 owners after I leave.
This CL was uploaded by git cl split.

R=dcastagna@chromium.org

Change-Id: Idb6a39f806f36f13814501e83aaf7a1a93e65819
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674637
Auto-Submit: Antoine Labour <piman@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Commit-Queue: Antoine Labour <piman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671829}

third_party/wayland/OWNERS

-reveman@chromium.org
+dcastagna@chromium.org
+oshima@chromium.org
 piman@chromium.org