Roll third_party/externals/swiftshader 540bdf92531d..77090261dabc (10 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/540bdf92531d..77090261dabc

git log 540bdf92531d..77090261dabc --date=short --first-parent --format='%ad %ae %s'
2020-03-25 capn@google.com Identify image views based on their state
2020-03-25 capn@google.com Provide packed VkFormat to uint8_t mapping
2020-03-25 capn@google.com Uniquely identify sampler state
2020-03-25 capn@google.com Split vk::Sampler state off into a structure
2020-03-25 capn@google.com Fix handling Memset<> assignment and comparison
2020-03-25 bclayton@google.com Add script for updating llvm 10
2020-03-25 amaiorano@google.com regres: add daily run against SwiftShader/Subzero
2020-03-25 bclayton@google.com CMake: Don't export LLVM_INCLUDE_DIR to PARENT_SCOPE
2020-03-25 bclayton@google.com CMake: Move LLVM rules out to third_party/llvm-7.0
2020-03-25 bclayton@google.com Add missing copyright header to CMakeLists.txt

Created with:
  gclient setdep -r third_party/externals/swiftshader@77090261dabc

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 robertphillips@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-Debian9-Clang-GCE-GPU-SwiftShader-x86_64-Debug-All-SwiftShader
Bug: None
Tbr: robertphillips@google.com
Change-Id: Ic47595afa9212e37b822fda7e0fd7578adfd5a63
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/279246
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 44c1420e..6d4d6f5 100644
--- a/DEPS
+++ b/DEPS
@@ -35,7 +35,7 @@
   "third_party/externals/spirv-cross"     : "https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Cross@dffd33dd9d19c798ffecc10f50e551b42d282628",
   "third_party/externals/spirv-headers"   : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Headers.git@29c11140baaf9f7fdaa39a583672c556bf1795a1",
   "third_party/externals/spirv-tools"     : "https://skia.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git@0c4feb643b89d1792b02f7cbef315e9d95633bd7",
-  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@540bdf92531d0c325d7b5c770ec33e869b56059f",
+  "third_party/externals/swiftshader"     : "https://swiftshader.googlesource.com/SwiftShader@77090261dabcf44c7b5a0f97bdf35e812a13a66a",
   #"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",