Add info unavailable error when info size is zero

Update buffer and platform tests accordingly
All tests passing in MacOSX
Fix int-size_t compare in image filter example kernel

Some OpenCL implementations complained about this warning although
the examples works fine.
Add check to avoid OSX bug in clGetEventProfilingInfo

- Dont consider info unavailable (i.e. size == 0) as an error
when profiling
- Improve error checking in ccl_prof_add_event
Add missing error checks to ccl_image_new_deprecated()

Fix bug in OCL stub: add specification of image type