Add a 'name' parameter to qemu_thread_create

If enabled, set the thread name at creation (on GNU systems with
  pthread_set_np)
Fix up all the callers with a thread name

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

thread-pool.c

@@ -140,7 +140,7 @@ static void do_spawn_thread(ThreadPool *pool)
     pool->new_threads--;
     pool->pending_threads++;
 
-    qemu_thread_create(&t, worker_thread, pool, QEMU_THREAD_DETACHED);
+    qemu_thread_create(&t, "worker", worker_thread, pool, QEMU_THREAD_DETACHED);
 }
 
 static void spawn_thread_bh_fn(void *opaque)