Roll third_party/externals/swiftshader 4c9f4a97ffe3..179c932426b3 (1 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/4c9f4a97ffe3..179c932426b3


git log 4c9f4a97ffe3..179c932426b3 --date=short --no-merges --format='%ad %ae %s'
2019-03-27 astrachan@google.com Handle NULL 'value' to eglGetSyncAttribKHR()


Created with:
  gclient setdep -r third_party/externals/swiftshader@179c932426b3

The AutoRoll server is located here: https://autoroll.skia.org/r/swiftshader-skia-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.

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Debian9-Clang-GCE-GPU-SwiftShader-x86_64-Debug-All-SwiftShader
TBR=stani@google.com

Change-Id: I106efbc7b4bdbedf3857613929fa31688c7ffda4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/204282
Reviewed-by: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>