libwebp-1.1.0

- 12/18/2019: version 1.1.0
  * API changes:
    - libwebp:
      WebPMalloc (issue #442)
    - extras:
      WebPUnmultiplyARGB
  * alpha decode fix (issue #439)
  * toolchain updates and bug fixes
    (chromium: #1026858, #1027136, #1027409, #1028620, #1028716, #995200)
    (oss-fuzz: #19430, #19447)

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