Log Message:
libwebp: updated to 1.2.0

version 1.2.0
* API changes:
  - libwebp:
    encode.h: add a qmin / qmax range for quality factor (cwebp adds -qrange)
* lossless encoder improvements
* SIMD support for Wasm builds
* add xcframeworkbuild.sh, supports Mac Catalyst builds
* import fuzzers from oss-fuzz & chromium
* webpmux: add an '-set loop <value>' option
* toolchain updates and bug fixes