Roll src/third_party/swiftshader 4584a9c2ccb9..afc52b0b26d7 (5 commits)

https://swiftshader.googlesource.com/SwiftShader.git/+log/4584a9c2ccb9..afc52b0b26d7

git log 4584a9c2ccb9..afc52b0b26d7 --date=short --no-merges --format='%ad %ae %s'
2019-11-25 bclayton@google.com Fix build: Do not return stack temporary.
2019-11-25 bclayton@google.com Fix chrome build: Use spaces (not tabs) in .gn files (2/2)
2019-11-25 bclayton@google.com Fix chrome build: Use spaces (not tabs) in .gn files
2019-11-22 chrisforbes@google.com Fix vkGetDescriptorSetLayoutSupport implementation
2019-11-22 srisser@google.com Log unsupported extensions used in pNext structs

Created with:
  gclient setdep -r src/third_party/swiftshader@afc52b0b26d7

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/swiftshader-chromium-autoroll
Please CC swiftshader-team+autoroll@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: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_chromium_msan_rel_ng;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Bug: chromium:b/139528538,chromium:b/139528538,chromium:b/139528538,chromium:b/145007346,chromium:b/139528538
Tbr: swiftshader-team+autoroll@google.com
Change-Id: I9666a01bb3e8a4d7ceac42e2b6854753e30f083e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932034Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#718563}

DEPS

@@ -188,7 +188,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.
-  'swiftshader_revision': '4584a9c2ccb9f2a7bc7cd3c55f5b95507901e035',
+  'swiftshader_revision': 'afc52b0b26d7d34baee77ce7b75aa3c5625abca9',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.