GL_IMG_texture_compression_pvrtc2
https://www.khronos.org/registry/OpenGL/extensions/IMG/IMG_texture_compression_pvrtc2.txt
GL_IMG_texture_compression_pvrtc2

	GL_COMPRESSED_RGBA_PVRTC_2BPPV2_IMG 0x9137
	GL_COMPRESSED_RGBA_PVRTC_4BPPV2_IMG 0x9138