Previous Fuchsia SDK versions provide an empty header file, for
convenience, but this is no longer the case.

Change-Id: Ica8d23cc38664b3ebe7093606da4c669d6043c73
Reviewed-on: https://chromium-review.googlesource.com/571763Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46688}