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/env/ocltst.cpp

@@ -109,7 +109,6 @@ class App {
         m_window(0),
         m_platform(platform) {
     // initialize OCLWrapper reference
-    m_wrapper = new OCLWrapper();
 
     // m_workers = Set of worker objects that are used to run a subtest from a
     // module
@@ -120,7 +119,8 @@ class App {
      * Force caltst to use 1 thread at a time in Windows
      * only contextual calls are thread safe currently
      */
-    m_numDevices = findAdapters(m_platform, m_useCPU, NULL);
+    m_numDevices = findAdapters(m_platform, m_useCPU, &mpform_id);
+    m_wrapper = new OCLWrapper(mpform_id);
     // m_numDevices = 1;
 
     // Report structure used to store the results of the tests