Do not enable GLES2 support. It is too experimental and broken (caused for example clutter-gst to not be able to compiler GLSL shaders, resulting in white video frames in cheese). Once this is checked in, it is CRUCIAL that clutter-gst is being REBUILT against this version, as this fix propagates (by means of header files) down to clutter-gst. Issue upstream reported / confirmed: bgo#685842 (forwarded request 151171 from vuntz)