Roll SwiftShader from 526b987888fb to 803ceb58c92c (2 revisions)

https://swiftshader.googlesource.com/SwiftShader.git/+log/526b987888fb..803ceb58c92c

2021-08-16 sugoi@google.com Xcb: Check if geom is valid before using it
2021-08-16 capn@google.com Fix integer overflow in vertex buffer access robustness check

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 jmadill@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 ANGLE: https://bugs.chromium.org/p/angleproject/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: jmadill@google.com
Change-Id: Ifc8ff74a3bc55a04fcf6968be64de55b23dafe76
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3099214
Commit-Queue: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>
Bot-Commit: angle-autoroll <angle-autoroll@skia-public.iam.gserviceaccount.com>

DEPS

@@ -491,7 +491,7 @@ deps = {
   },
 
   'third_party/SwiftShader': {
-    'url': '{swiftshader_git}/SwiftShader@526b987888fbeb5c952912d41265156d53e9e849',
+    'url': '{swiftshader_git}/SwiftShader@803ceb58c92cc4c817685efa896c8e7421a86cc2',
     'condition': 'not build_with_chromium',
   },