Roll external/skia c712e962b647..87f94cdc94bc (25 commits)

https://skia.googlesource.com/skia.git/+log/c712e962b647..87f94cdc94bc

2019-09-26 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader cc3f09861685..30d3c8afe19c (2 commits)
2019-09-26 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src fb8fbb18d6f2..fbc0a229ff3c (465 commits)
2019-09-26 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-09-26 jcgregorio@google.com Fix HOME directory in Docker containers built under cloudbuild.
2019-09-25 herb@google.com Move SkScalerContextEffects to SkScalerContext.h
2019-09-25 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-09-25 csmartdalton@google.com Move the msaa dirty rect to GrRenderTargetProxy
2019-09-25 mtklein@google.com clean up for SSSE3 bilerp
2019-09-25 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-09-25 nifong@google.com Add a test that draws subpictures within an MSKP and make it pass.
2019-09-25 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-09-25 herb@google.com Use constexpr version of min/max
2019-09-25 brianosman@google.com In AAConvexPathRenderer, don't assume that path direction can be computed
2019-09-25 nigeltao@google.com Fix calls to deprecated Wuffs API
2019-09-25 mtklein@google.com cut another multiply in SSE2 bilerp
2019-09-25 nifong@google.com Add tests that loads mskp and changes frame.
2019-09-25 mtklein@google.com cut a multiply in SSE2 bilerp
2019-09-25 csmartdalton@google.com Don't submit msaa resovle command buffers except for external IO
2019-09-25 herb@google.com Add helper SkMakeZip
2019-09-25 mtklein@google.com comment and TODO bilerp code
2019-09-25 herb@google.com Add project declaration for CMake
2019-09-25 mtklein@google.com opt skottie_tool into thread-local strike caches
2019-09-25 robertphillips@google.com Split out check_base_readbacks sub-test in BackendAllocation tests
2019-09-25 mtklein@google.com dump frame time stats in skottie_tool
2019-09-25 brianosman@google.com Particles: Added particle flags for tracking state (one-time triggers, etc)

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: I2980485f9a06ea38dcc7ced46ecad44165ab08ee
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.