Instead use the canonical empty fixed array. Some code assumes
that this is the only fixed array of length 0.

Bug: chromium:843062
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: If780acf50147c061a81f2ff2b31779fbd1c78559
Reviewed-on: https://chromium-review.googlesource.com/1064052Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53320}