Fix the thread handle that arrives too late

src/xtd.core/src/xtd/threading/thread.cpp

@@ -521,6 +521,7 @@ bool thread::join_all_ptr(const std::vector<thread*>& threads, int32 millisecond
 
 void thread::thread_proc() {
   if (data_->thread_id == invalid_thread_id) data_->thread_id = get_current_thread_id();
+  if (data_->handle == invalid_handle) data_->handle = get_current_thread_handle();
   if (!data_->name.empty()) native::thread::set_current_thread_name(data_->name);
   if (data_->priority != xtd::threading::thread_priority::normal) native::thread::set_priority(data_->handle, as<int32>(data_->priority));