Roll Skia from c244996e79d6 to c6d971f87d12 (1 revision) (flutter/engine#48268)

https://skia.googlesource.com/skia.git/+log/c244996e79d6..c6d971f87d12

2023-11-21 briansalomon@gmail.com Fix Graphite-Dawn wasm build

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC brianosman@google.com,jacksongardner@google.com,jamesgk@google.com,rmistry@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Skia: https://bugs.chromium.org/p/skia/issues/entry
To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

DEPS

@@ -18,7 +18,7 @@ vars = {
   'llvm_git': 'https://llvm.googlesource.com',
   # OCMock is for testing only so there is no google clone
   'ocmock_git': 'https://github.com/erikdoe/ocmock.git',
-  'skia_revision': 'c244996e79d6ce0d523f60af2d9575206ddec5b1',
+  'skia_revision': 'c6d971f87d12cdf14c691768bfbc84b1708cc389',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.

engine/src/flutter/ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: 42035afbaf34c986c9b1824fde519e2b
+Signature: 52c9f5578d7eb029f92c49d2603ea9fc
 
 ====================================================================================================
 LIBRARY: etc1