Roll Fuchsia SDK from 0.20200915.1.1 to 0.20200915.2.1

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/fuchsia-sdk-chromium-autoroll
Please CC cr-fuchsia+bot@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:fuchsia-arm64-cast;luci.chromium.try:fuchsia-x64-cast
Tbr: cr-fuchsia+bot@chromium.org
Change-Id: I46793279dae557c6a6b26828f1d8fcaa2d836e70
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2412565
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#807236}