Does Mavericks support OpenCL?
Mavericks supports OpenCL but your GPU is not compatible (there are no OpenCL drivers for it).

Try running the example with CL_DEVICE_TYPE_CPU, Simply set the variable gpu to 0;

int gpu = 0;


This paper says OpenCL Support on Sandy Bridge is limited: 


  3rd Generation Intel® Core™ Processors with the Intel® HD Graphics 4000/2500


Your Macbook Air is equipped with HD Graphics 3000.