GL_SGIX_async_pixel
https://www.khronos.org/registry/OpenGL/extensions/SGIX/SGIX_async_pixel.txt
GL_SGIX_async_pixel

	GL_ASYNC_TEX_IMAGE_SGIX 0x835C
	GL_ASYNC_DRAW_PIXELS_SGIX 0x835D
	GL_ASYNC_READ_PIXELS_SGIX 0x835E
	GL_MAX_ASYNC_TEX_IMAGE_SGIX 0x835F
	GL_MAX_ASYNC_DRAW_PIXELS_SGIX 0x8360
	GL_MAX_ASYNC_READ_PIXELS_SGIX 0x8361
