ocl-icd: free OpenCL ICD Loader

OpenCL implementations are provided as ICD (Installable Client Driver). An
OpenCL program can use several ICD thanks to the use of an ICD Loader as
provided by this project. This free ICD Loader can load any (free or non free)
ICD.

NOTE: ocl-icd should not be needed on systems where graphics drivers
by AMD or Nvidia already provide an OpenCL ICD Loader implementation.
To check if you already have an ICD loader, run this as root:

  ldconfig -p | grep -i opencl

If nothing is printed out, then your system probably lacks an ICD
implementation (libOpenCL.so* objects) and you need this package.

If something is printed out, then you don't need this package, as it 
would probably overwrite the ICD loader that came with your graphics 
drivers.