Use std::thread for userevents_multithreaded test (#824)

The genericThread abstraction is not necessary now that C++11 is
required.

test_conformance/events/test_userevents_multithreaded.cpp

@@ -16,28 +16,19 @@
 #include "testBase.h"
 #include "action_classes.h"
 #include "harness/conversions.h"
-#include "harness/genericThread.h"
+
+#include <thread>
 
 #if !defined (_MSC_VER)
     #include <unistd.h>
 #endif // !_MSC_VER
 
-class releaseEvent_thread : public genericThread
+void trigger_user_event(cl_event *event)
 {
-    public:
-        releaseEvent_thread( cl_event *event ) : mEvent( event ) {}
-
-        cl_event * mEvent;
-
-    protected:
-        virtual void *    IRun( void )
-        {
-            usleep( 1000000 );
-            log_info( "\tTriggering gate from separate thread...\n" );
-            clSetUserEventStatus( *mEvent, CL_COMPLETE );
-            return NULL;
-        }
-};
+    usleep(1000000);
+    log_info("\tTriggering gate from separate thread...\n");
+    clSetUserEventStatus(*event, CL_COMPLETE);
+}
 
 int test_userevents_multithreaded( cl_device_id deviceID, cl_context context, cl_command_queue queue, int num_elements )
 {
@@ -66,14 +57,14 @@ int test_userevents_multithreaded( cl_device_id deviceID, cl_context context, cl
     }
 
     // Now, instead of releasing the gate, we spawn a separate thread to do so
-    releaseEvent_thread thread( &gateEvent );
     log_info( "\tStarting trigger thread...\n" );
-    thread.Start();
+    std::thread thread(trigger_user_event, &gateEvent);
 
     log_info( "\tWaiting for actions...\n" );
     error = clWaitForEvents( 3, &actionEvents[ 0 ] );
     test_error( error, "Unable to wait for action events" );
 
+    thread.join();
     log_info( "\tActions completed.\n" );
 
     // If we got here without error, we're good