GL_NV_texture_compression_latc
http://www.opengl.org/registry/specs/NV/texture_compression_latc.txt
GL_NV_texture_compression_latc

	GL_COMPRESSED_LUMINANCE_LATC1_NV 0x8C70
	GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_NV 0x8C71
	GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_NV 0x8C72
	GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_NV 0x8C73
