gettextsubimage: verify zoffset and depth are correct

gettextsubimage: verify zoffset and depth are correct

According to OpenGL 4.6 spec, section 8.11.4 ("Texture Image Queries"),
relative to errors for GetTextureSubImage() function:

  "An INVALID_VALUE error is generated if the effective target is
   TEXTURE_1D and either yoffset is not zero, or height is not one.

   An INVALID_VALUE error is generated if the effective target is
   TEXTURE_1D, TEXTURE_1D_ARRAY, TEXTURE_2D or TEXTURE_RECTANGLE, and
   either zoffset is not zero, or depth is not one."

The commit fixes the check for height and depth.

This fixes arb_get_texture_sub_image piglit tests.

Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>