Roll SwiftShader from dca80fc3a894 to 21201ed7a441 (1 revision)

https://swiftshader.googlesource.com/SwiftShader.git/+log/dca80fc3a894..21201ed7a441

2023-02-27 bclayton@google.com marl: emulate thread_local with pthreads

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/swiftshader-dawn-autoroll
Please CC dsinclair@google.com,webgpu-developers@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in SwiftShader: https://bugs.chromium.org/p/swiftshader/issues/entry
To file a bug in Dawn: https://bugs.chromium.org/p/dawn/issues/entry

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/+doc/main/autoroll/README.md

Bug: None
Tbr: dsinclair@google.com
Change-Id: Ie52d778f62924eb9dfd87e3151713381fbc1e9a1
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/121840
Commit-Queue: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Bot-Commit: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>
Reviewed-by: dan sinclair <dsinclair@google.com>

DEPS

@@ -137,7 +137,7 @@ deps = {
   },
 
   'third_party/swiftshader': {
-    'url': '{swiftshader_git}/SwiftShader@dca80fc3a894149ecf4d5cd4d4fe665fe0274bb3',
+    'url': '{swiftshader_git}/SwiftShader@21201ed7a441ba06f8b699c6fe5d71c664eb0b4e',
     'condition': 'dawn_standalone',
   },