Roll third_party/externals/swiftshader b4a27407e2be..ba0c95eb406f (5 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/b4a27407e2be..ba0c95eb406f

git log b4a27407e2be..ba0c95eb406f --date=short --first-parent --format='%ad %ae %s'
2020-04-07 bclayton@google.com Regres: Fix uncovered calculations after optimizations
2020-04-07 bclayton@google.com Regres: Optimize coverage processing
2020-04-07 bclayton@google.com Regres: Re-populate treeFile.allSpans on parse.
2020-04-07 bclayton@google.com Update third_party/marl/BUILD.gn with new files
2020-04-07 bclayton@google.com Update Marl to 539094011

Created with:
  gclient setdep -r third_party/externals/swiftshader@ba0c95eb406f

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/swiftshader-skia-autoroll
Please CC csmartdalton@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: skia/skia.primary:Test-Debian10-Clang-GCE-GPU-SwiftShader-x86_64-Debug-All-SwiftShader
Bug: None
Tbr: csmartdalton@google.com
Change-Id: Ie36d699c03b21660900c699aadc58b84562c07a9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/282227
Reviewed-by: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 7478b85..3330311 100644
--- a/DEPS
+++ b/DEPS
@@ -37,7 +37,7 @@
   "third_party/externals/spirv-cross"     : "https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Cross@871c85d7f0edc6b613e3959bc51d13bfbc2fe2df",
   "third_party/externals/spirv-headers"   : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Headers.git@f8bf11a0253a32375c32cad92c841237b96696c0",
   "third_party/externals/spirv-tools"     : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git@1c8bda3721e6b9302f694b58c26d32eff341b126",
-  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@b4a27407e2be535f44b960929e7c4e6c0532f862",
+  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@ba0c95eb406fb2c36cb2d1515765f4de82cbed9b",
   #"third_party/externals/v8"              : "https://chromium.googlesource.com/v8/v8.git@5f1ae66d5634e43563b2d25ea652dfb94c31a3b4",
   "third_party/externals/wuffs"           : "https://skia.googlesource.com/external/github.com/google/wuffs.git@4080840928c0b05a80cda0d14ac2e2615f679f1a",
   "third_party/externals/zlib"            : "https://chromium.googlesource.com/chromium/src/third_party/zlib@47af7c547f8551bd25424e56354a2ae1e9062859",