Roll external/skia 86c9c95b2..86e0a0fc4 (6 commits)

https://skia.googlesource.com/skia.git/+log/86c9c95b2..86e0a0fc4

2019-02-22 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader e53533d6fdf9..d2452555986f (2 commits)
2019-02-22 reed@google.com add gm to test backdrop blurs and clipping/hintrects
2019-02-22 herb@google.com Change SDFT to use a bulk api for the callback
2019-02-22 fmalita@chromium.org Revert "[skottie] Add tritone layer effect support"
2019-02-22 fmalita@chromium.org [skottie] Add tritone layer effect support
2019-02-22 halcanary@google.com SkShaper/public.bzl fix

The AutoRoll server is located here: https://autoroll-internal.skia.org/r/android-master-autoroll

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

Test: Presubmit checks will test this change.
Change-Id: I2d2d9cf3e699833af7e56ac0ff32ffa2c37d3a44
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.