Roll third_party/externals/swiftshader 3e2a478..abb5785 (3 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/3e2a4780e607..abb57857c536


git log 3e2a478..abb5785 --date=short --no-merges --format='%ad %ae %s'
2019-03-12 bclayton@google.com tests: Add a unit test for a simple memcpy compute shader
2019-03-12 bclayton@google.com Vulkan: Very rough first implementation of compute shaders
2019-03-12 bclayton@google.com Add vulkan unit tests to Kokoro


Created with:
  gclient setdep -r third_party/externals/swiftshader@abb57857c536

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=benjaminwagner@google.com

Change-Id: I5da79fd9b64933d79dc746a6cdf586db36e0f2a9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/200328
Reviewed-by: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>

DEPS

@@ -28,7 +28,7 @@ deps = {
   "third_party/externals/sfntly"          : "https://chromium.googlesource.com/external/github.com/googlei18n/sfntly.git@b55ff303ea2f9e26702b514cf6a3196a2e3e2974",
   "third_party/externals/spirv-headers"   : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Headers.git@661ad91124e6af2272afd00f804d8aa276e17107",
   "third_party/externals/spirv-tools"     : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git@e9e4393b1c5aad7553c05782acefbe32b42644bd",
-  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@3e2a4780e607eb2b87232e484de113d91021a3ec",
+  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@abb57857c5369cecdf048de8b9dc8f530fb37849",
   #"third_party/externals/v8"              : "https://chromium.googlesource.com/v8/v8.git@5f1ae66d5634e43563b2d25ea652dfb94c31a3b4",
   "third_party/externals/wuffs"           : "https://skia.googlesource.com/external/github.com/google/wuffs.git@ae6e8db4ad4236654e7b8c68d24f41a37e5f4f96",
   "third_party/externals/zlib"            : "https://chromium.googlesource.com/chromium/src/third_party/zlib@47af7c547f8551bd25424e56354a2ae1e9062859",