ASTC image compression and decompression library headers

 The Adaptive Scalable Texture Compression (ASTC) format, developed by
 Arm® and AMD, has been adopted as an official extension to the Open GL®,
 OpenGL ES, and Vulkan® graphics APIs. It provides a major step forward
 both in terms of image quality at a given bitrate, and in terms of the
 format and bitrate flexibility available to content creators. This
 allows more assets to use compression, often at a reduced bitrate
 compared to legacy formats, reducing memory bandwidth and energy
 consumption.
 .
 This package provides the development headers to include ASTC support
 in other applications.