[libwebp] Add all target platforms for testing

Change-Id: I4ebde9c6a2d31907b67cf422154a2d4a70d038a6
Bug: b:185520507
Reviewed-on: https://chromium-review.googlesource.com/c/codecs/infra/+/3271374
Reviewed-by: Bharath Chandra Elluru <ellurubharath@google.com>
Reviewed-by: James Zern <jzern@google.com>
Commit-Queue: Roberto Alanis Baez <alanisbaez@google.com>
5 files changed