slackbuilds_ponce/libraries/libspng

lib**spng** (**s**imple **png**) is a C library for reading and
writing Portable Network Graphics (PNG) format files with a focus on
security and ease of use.

libspng is an alternative to libpng, the projects are separate and the
APIs are not compatible.

The goal is to provide a fast PNG library with a simpler API than
https://github.com/glennrp/libpng/blob/libpng16/png.h, it outperforms
the reference implementation in common use cases.

libspng can be used by xpra for better speed.