SWDEV-493913 - Replaced calls to clGetExtensionFunctionAddress in ocltst

Replaced clGetExtensionFunctionAddress calls with
clGetExtensionFunctionAddressForPlatform to ensure
interoperability with distribution ICD loaders.

Change-Id: I560a62459f2ad222750e65e869b98d6b6ec56665

opencl/tests/ocltst/include/OCLWrapper.h

@@ -103,7 +103,7 @@ typedef CL_API_ENTRY cl_int(CL_API_CALL *clSetDeviceClockModeAMD_fn)(
 
 class OCLWrapper {
  public:
-  OCLWrapper();
+  OCLWrapper(cl_platform_id);
 
   ~OCLWrapper() {}