Add debug checking of time stamps validity.

Can only check that the signal has some time stamp, can't check if
the translating agent matches the last used agent or not.

Change-Id: I62943a864318808059c617280bb65a269dfadd1b

runtime/hsa-runtime/core/runtime/amd_gpu_agent.cpp

@@ -1034,6 +1034,11 @@ void GpuAgent::TranslateTime(core::Signal* signal,
     SyncClocks();
   }
 
+  if ((signal->signal_.start_ts == 0) || (signal->signal_.end_ts == 0) ||
+      (signal->signal_.start_ts > t1_.GPUClockCounter) ||
+      (signal->signal_.end_ts > t1_.GPUClockCounter))
+    debug_print("Signal %p time stamps may be invalid.", &signal->signal_);
+
   time.start = uint64_t(
       (double(int64_t(t0_.SystemClockCounter - t1_.SystemClockCounter)) /
        double(int64_t(t0_.GPUClockCounter - t1_.GPUClockCounter))) *