SWDEV-510319 - Fixed random segfaults in graph tests

This change fixes random segfaults in graph tests that
are seen after the change make internal callbacks non-blocking.
The callback thread that decreases the GraphExec ref count
may now run after the runtime shutdown. This can cause a segfault
because the hip::device that is accessed in GraphExec destructor
is already destroyed during runtime shutdown. This patch ensures
that the hip::device object  stays alive until after the
callback thread completes.

Change-Id: I75a6ac01f27a0b2250bbd10ed389ebfb322927af

rocclr/device/rocm/rocvirtual.cpp

@@ -235,11 +235,13 @@ bool HsaAmdSignalHandler(hsa_signal_value_t value, void* arg) {
   // Reset last used SDMA engine mask
   gpu->setLastUsedSdmaEngine(0);
 
+  bool isBlocking = ts->GetBlocking();
+
   // Update the batch, since signal is complete
   gpu->updateCommandsState(ts->command().GetBatchHead());
 
   // Reset API callback signal. It will release AQL queue and start commands processing
-  if (callback_signal.handle != 0 && ts->GetBlocking()) {
+  if (callback_signal.handle != 0 && isBlocking) {
     hsa_signal_subtract_relaxed(callback_signal, 1);
   }