Roll Flutter Engine from 4a65910f0ab2 to 9796817fb6e2 (2 revisions) (#136990)

https://github.com/flutter/engine/compare/4a65910f0ab2...9796817fb6e2

2023-10-20 jiahaog@users.noreply.github.com Update buildroot to remove `-Wno-c99-designator` (flutter/engine#47145)
2023-10-20 skia-flutter-autoroll@skia.org Roll Skia from ca69b04f7dd2 to cf2131f85d57 (2 revisions) (flutter/engine#47173)

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

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

bin/internal/engine.version

-4a65910f0ab2c4b5ddb1029add8095ad16979278
+9796817fb6e2790c15d5b52e442225e6e77240d3