Roll external/skia 93edd9eb445a..c2ec9bfe1bb5 (2 commits)

https://skia.googlesource.com/skia.git/+log/93edd9eb445a..c2ec9bfe1bb5

2019-08-31 skia-recreate-skps@skia-swarming-bots.iam.gserviceaccount.com Update Go deps
2019-08-30 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://skia-autoroll.corp.goog/r/android-master-autoroll
Please CC djsollen@google.com 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/+/master/autoroll/README.md

Test: Presubmit checks will test this change.
Change-Id: I1ade43e654d18af1839dc6771f2c976c1db52ae6
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.