[SYCL][Graph] Fixes multithread finalize unitest bug (#314)

* [SYCL][Graph] Fixes multithread finalize unitest bug

std::map insertions are not thread-safe causing an issue in the multithread finalize test.
This commit adds a mutex to prevent races when inserting data in the map.

* Update sycl/unittests/Extensions/CommandGraph.cpp

Co-authored-by: Ewan Crawford <ewan@codeplay.com>

---------

Co-authored-by: Ewan Crawford <ewan@codeplay.com>

sycl/unittests/Extensions/CommandGraph.cpp

@@ -1931,18 +1931,21 @@ TEST_F(MultiThreadGraphTest, RecordAddNodesInOrderQueue) {
 TEST_F(MultiThreadGraphTest, Finalize) {
  addKernels(Graph);
 
+ std::mutex MutexMap;
+
  std::map<int,
  experimental::command_graph<experimental::graph_state::executable>>
  GraphsExecMap;
  auto FinalizeGraph = [&](int ThreadNum) {
  SyncPoint.wait();
  auto GraphExec = Graph.finalize();
+ Queue.submit([&](sycl::handler &CGH) { CGH.ext_oneapi_graph(GraphExec); });
 
+ std::lock_guard<std::mutex> Guard(MutexMap);
  GraphsExecMap.insert(
  std::map<int, experimental::command_graph<
  experimental::graph_state::executable>>::
  value_type(ThreadNum, GraphExec));
- Queue.submit([&](sycl::handler &CGH) { CGH.ext_oneapi_graph(GraphExec); });
  };
 
  for (unsigned i = 0; i < NumThreads; ++i) {