Merge "external/webp: update to v1.1.0-28-g55a080e5" am: c4147d8f00 am: 663b190f19 am: 7d93739593

Original change: https://android-review.googlesource.com/c/platform/external/webp/+/1425968

Change-Id: I461df26af5bab2bc8c7967b6315d13556419e4e2