Roll src/third_party/swiftshader 7e01e4e0d6b7..3971b19ba242 (2 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/7e01e4e0d6b7..3971b19ba242


git log 7e01e4e0d6b7..3971b19ba242 --date=short --no-merges --format='%ad %ae %s'
2019-05-28 chrisforbes@google.com Fix accidentally considering Workgroup to be explicit layout
2019-05-28 bclayton@google.com Reactor: Add swizzle op for UInt4.


Created with:
  gclient setdep -r src/third_party/swiftshader@3971b19ba242

The AutoRoll server is located here: https://autoroll.skia.org/r/swiftshader-chromium-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=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG=chromium:b/133509497
TBR=swiftshader-team+autoroll@google.com

Change-Id: I47ed07d6257c69a843ae7f433e6fe8d0a2d7d91b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1631146Reviewed-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@{#663848}

DEPS

@@ -154,7 +154,7 @@ 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': '7e01e4e0d6b77d32377cf1e5912f1f053fe79356',
+  'swiftshader_revision': '3971b19ba24228787897efc59e265964b8b5a17f',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.