Roll src/third_party/swiftshader 855e8b1bc29d..aaa64b76c0b4 (6 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/855e8b1bc29d..aaa64b76c0b4

git log 855e8b1bc29d..aaa64b76c0b4 --date=short --no-merges --format='%ad %ae %s'
2019-11-01 amaiorano@google.com Modify Blitter to implement FunctionT
2019-11-01 amaiorano@google.com Modify SetupRoutine to implement FunctionT
2019-11-01 amaiorano@google.com Modify PixelRoutine to implement FunctionT
2019-11-01 amaiorano@google.com Modify VertexRoutine to implement FunctionT
2019-11-01 amaiorano@google.com ReactorUnitTests: use FunctionT
2019-11-01 amaiorano@google.com Reactor: add type-safe FunctionT and RoutineT

Created with:
  gclient setdep -r src/third_party/swiftshader@aaa64b76c0b4

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/swiftshader-chromium-autoroll
Please CC swiftshader-team+autoroll@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

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_chromium_msan_rel_ng;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
TBR=swiftshader-team+autoroll@google.com

Bug: chromium:b/143479561,chromium:b/143479561,chromium:b/143479561,chromium:b/143479561,chromium:b/143479561,chromium:b/143479561
Change-Id: Idffec085f5c466a7cea070c82320656bcc0b87b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895875Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#711873}

DEPS

@@ -188,7 +188,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.
-  'swiftshader_revision': '855e8b1bc29daf4cd1ad410cae0171e4f58523c2',
+  'swiftshader_revision': 'aaa64b76c0b40c2958a18cfdc623157c8c6e1b7d',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.