Omitting PV_DIR when using OpenCL causes a compile-time error, so error is reported by #error directive instead of printing error message at runtime
Omitting PV_DIR when using OpenCL causes a compile-time error, so error is reported by #error directive instead of printing error message at runtime

git-svn-id: 602a26e73ae9f2a14e2bb95676f2e137fcc39919@9195 7c0444ca-5550-0410-9008-faecdbe78eb5

dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV