Improve AImageDecoder fuzzer

Bug: 169137236
Bug: 169139756
Test: this (fuzzer)

Extend the fuzzer to test animations.

Also test a lossless webp, left out of
Ib227639bf8da75f0e8e31e216bc6d1371e24cb75.

Change-Id: I81d35d6fa7d560b33b6a2b5d6c1992cbdd77bc87
2 files changed