sapi: Call CoInitializeEx/CoUninitialize in async_worker.

dlls/sapi/async.c

@@ -71,6 +71,7 @@ static void CALLBACK async_worker(TP_CALLBACK_INSTANCE *instance, void *ctx)
     HANDLE handles[2] = { queue->cancel, queue->wait };
     DWORD ret;
 
+    CoInitializeEx(NULL, COINIT_MULTITHREADED);
     SetEvent(queue->ready);
 
     for (;;)
@@ -99,6 +100,7 @@ static void CALLBACK async_worker(TP_CALLBACK_INSTANCE *instance, void *ctx)
 
 cancel:
     async_empty_queue(queue);
+    CoUninitialize();
     TRACE("cancelled.\n");
     SetEvent(queue->ready);
 }