Roll third_party/SwiftShader 74d3f371f201..f50cc82b3bed (6 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/74d3f371f201..f50cc82b3bed

git log 74d3f371f201..f50cc82b3bed --date=short --first-parent --format='%ad %ae %s'
2020-02-20 amaiorano@google.com Subzero: add support for large stacks on Windows
2020-02-20 sugoi@google.com VK_EXT_shader_stencil_export support
2020-02-20 bclayton@google.com Remove rr::Thread
2020-02-20 capn@google.com Support JIT on a separate thread
2020-02-20 sugoi@google.com Revert "VK_EXT_shader_stencil_export support"
2020-02-20 sugoi@google.com VK_EXT_shader_stencil_export support

Created with:
  gclient setdep -r third_party/SwiftShader@f50cc82b3bed

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

Bug: None
Tbr: cwallez@google.com
Change-Id: Iee314936392d69caf6fe77de0cbd9fd64b61aae5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2068202
Reviewed-by: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 9a8d598..0a7f209 100644
--- a/DEPS
+++ b/DEPS
@@ -182,7 +182,7 @@
   },
 
   'third_party/SwiftShader': {
-    'url': '{swiftshader_git}/SwiftShader@74d3f371f2015deeedb985a8b24ba242ea65caef',
+    'url': '{swiftshader_git}/SwiftShader@f50cc82b3bed049f50ce8e530e3be5db307baa64',
     'condition': 'not build_with_chromium',
   },