external/webp: update to v1.0.3

clear local cherry-picks, general lossless encoder/decoder speedups

Test: aosp_arm-eng aosp_arm64-eng aosp_x86-eng aosp_x86_64-eng
      aosp_crosshatch-userdebug build

Change-Id: Iaefab737e4099632b79977f4c930b9bfc3444311
38 files changed