libwebp-1.2.3

- 6/30/2022: version 1.2.3
  This is a binary compatible release.
  * security fix for lossless encoder (#565, chromium:1313709)
  * improved progress granularity in WebPReportProgress() when using lossless
  * improved precision in Sharp YUV (-sharp_yuv) conversion
  * many corrections to webp-lossless-bitstream-spec.txt (#551)
  * crash/leak fixes on error/OOM and other bug fixes (#558, #563, #569, #573)

1. 7c76255 autoconf: update ax_pthread.m4 by James Zern · 12 years ago
2. 1d40a8b configure: add pthread detection by James Zern · 13 years ago
3. b247a3b Create the m4 directory, and also place .gitignore in there for libtool. by Pascal Massimino · 15 years ago