On GLES *Rect textures are not supported and emulated by using a normal
2D texture. Therefore, the texture coordinates must be normalized for
these cases and the LOD must be set to 0.

Fixes: piglits
   textureGather with 2DRECT texture
   arb_fragment_program_shadow/tex-shadow2drect
   arb_fragment_program_shadow/txp-shadow2drect
   glsl-fs-texture2drect -proj3 and -proj4

Related: #81  (some non-shader tests still fail for rect textures)

v2: - Reorder some conditions to make the control flow easier to follow
    - correct WS (both Gurchetan)

Remark: For some of these piglits one must currently force GL 3.3 in the
        guest, otherwise they fail because of GLSL version 1.50 not being
        supported.
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: <Gurchetan Singh gurchetansingh@chromium.org>