GL_SGIS_generate_mipmap
https://www.khronos.org/registry/OpenGL/extensions/SGIS/SGIS_generate_mipmap.txt
GL_SGIS_generate_mipmap

	GL_GENERATE_MIPMAP_SGIS 0x8191
	GL_GENERATE_MIPMAP_HINT_SGIS 0x8192