GL_EXT_texture_compression_s3tc_srgb
https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_s3tc_srgb.txt
GL_EXT_texture_compression_s3tc_srgb

	GL_COMPRESSED_SRGB_S3TC_DXT1_EXT 0x8C4C
	GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT 0x8C4D
	GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT 0x8C4E
	GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT 0x8C4F