command_buffer_event_sync.cpp: add delay for testing clSetEventCallback

according to specification, these can be executed asynchronously
by the OpenCL runtime.

test_conformance/extensions/cl_khr_command_buffer/command_buffer_event_sync.cpp

@@ -18,6 +18,8 @@
 #include "procs.h"
 
 #include <vector>
+#include <thread>
+#include <chrono>
 
 //--------------------------------------------------------------------------
 enum class EventMode
@@ -416,6 +418,12 @@ struct CommandBufferEventSync : public BasicCommandBufferTest
  error = clFinish(queue);
  test_error(error, "clFinish failed");
 
+ for (unsigned i = 0; i < 30; ++i)
+ {
+ std::this_thread::sleep_for(std::chrono::milliseconds(100));
+ if (confirmation) break;
+ }
+
  // verify the result
  if (!confirmation)
  {
@@ -763,6 +771,12 @@ struct CommandBufferEventSync : public BasicCommandBufferTest
  error = clFinish(queue);
  test_error(error, "clFinish failed");
 
+ for (unsigned i = 0; i < 30; ++i)
+ {
+ std::this_thread::sleep_for(std::chrono::milliseconds(100));
+ if (confirmation) break;
+ }
+
  // verify the result
  if (!confirmation)
  {