Native bindings to the EXT_texture_filter_minmax extension.

In unextended OpenGL 4.3, minification and magnification filters such as LINEAR allow texture lookups to returned a filtered texel value produced by computing an weighted average of a collection of texels in the neighborhood of the texture coordinate provided.

This extension provides a new texture and sampler parameter (TEXTURE_REDUCTION_MODE_EXT) which allows applications to produce a filtered texel value by computing a component-wise minimum (MIN) or maximum (MAX) of the texels that would normally be averaged. The reduction mode is orthogonal to the minification and magnification filter parameters. The filter parameters are used to identify the set of texels used to produce a final filtered value; the reduction mode identifies how these texels are combined.