Add updated platform support for the Khronos approved ICD model so AMD and...

Add updated platform support for the Khronos approved ICD model so AMD and newer Nvidia drivers on Windows/Linux will work.  Haven't tested Apple

platforms/opencl/src/OpenCLContext.cpp

@@ -43,7 +43,11 @@ using namespace std;
 
 OpenCLContext::OpenCLContext(int numParticles, int deviceIndex) : time(0.0), stepCount(0), computeForceCount(0) {
     try {
-        context = cl::Context(CL_DEVICE_TYPE_ALL);
+		std::vector<cl::Platform> platforms;	
+		cl::Platform::get(&platforms);	
+		cl_context_properties cprops[] = {CL_CONTEXT_PLATFORM, (cl_context_properties)platforms[0](), 0 };
+        context = cl::Context(CL_DEVICE_TYPE_ALL, cprops);
+
         vector<cl::Device> devices = context.getInfo<CL_CONTEXT_DEVICES>();
         const int minThreadBlockSize = 32;
         if (deviceIndex < 0 || deviceIndex >= (int) devices.size()) {