libwebp-1.2.2

- 1/11/2022: version 1.2.2
  This is a binary compatible release.
  * webpmux: add "-set bgcolor A,R,G,B"
  * add ARM64 NEON support for MSVC builds (#539)
  * fix duplicate include error in Xcode when using multiple XCFrameworks in a
    project (#542)
  * doc updates and bug fixes (#538, #544, #548, #550)

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