GL_MESAX_texture_stack
http://www.opengl.org/registry/specs/MESAX/texture_stack.txt
GL_MESAX_texture_stack
GL_TEXTURE_1D_STACK_MESAX 0x8759
GL_TEXTURE_2D_STACK_MESAX 0x875A
GL_PROXY_TEXTURE_1D_STACK_MESAX 0x875B
GL_PROXY_TEXTURE_2D_STACK_MESAX 0x875C
GL_TEXTURE_1D_STACK_BINDING_MESAX 0x875D
GL_TEXTURE_2D_STACK_BINDING_MESAX 0x875E