Roll SwiftShader from 6a8a74986c35 to 3b2cd31c7400 (9 revisions)

https://swiftshader.googlesource.com/SwiftShader.git/+log/6a8a74986c35..3b2cd31c7400

2020-07-26 capn@google.com Update Vulkan headers to version 1.2.148
2020-07-26 capn@google.com Refactor native instruction intrinsics
2020-07-24 amaiorano@google.com Delete third_party/llvm-7.0
2020-07-23 sugoi@google.com Add basic support for VK_EXT_debug_utils
2020-07-23 srisser@google.com Add support for depthBiasClamp
2020-07-23 spang@chromium.org Silence warnings on dedicated external memory allocations
2020-07-23 capn@google.com Regres: Roll dEQP to 1.2.3
2020-07-23 amaiorano@google.com Fix CMake failure on MacOS when PowerVR submodule is checked out
2020-07-23 capn@google.com Don't update CMake for Windows Kokoro builds

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 timvp@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/+doc/master/autoroll/README.md

Bug: None
Tbr: timvp@google.com
Change-Id: I51df404988b223be4c2e2a3d30891c86797e4b8f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2319979
Reviewed-by: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>

DEPS

@@ -215,7 +215,7 @@ deps = {
   },
 
   'third_party/SwiftShader': {
-    'url': '{swiftshader_git}/SwiftShader@6a8a74986c357b0c6fa0dfd2b4b9230af8d39d1a',
+    'url': '{swiftshader_git}/SwiftShader@3b2cd31c740071d7272029f6fbcef43ffc200f12',
     'condition': 'not build_with_chromium',
   },