Native bindings to the EXT_texture_mirror_clamp_to_edge extension.

EXT_texture_mirror_clamp_to_edge extends the set of texture wrap modes to include an additional mode (MIRROR_CLAMP_TO_EDGE_EXT) that effectively uses a texture map twice as large as the original image in which the additional half of the new image is a mirror image of the original image.

This new mode relaxes the need to generate images whose opposite edges match by using the original image to generate a matching "mirror image". This mode allows the texture to be mirrored only once in the negative s, t, and r directions.