rcu: fixes test-logging.c by call drain_call_rcu before rmdir_full

drain_call_rcu is necessary on win32, because under win32, if you
don't close the file before remove it, the remove would be fail.

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Message-Id: <20200915121318.247-23-luoyonggang@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/test-logging.c

@@ -210,6 +210,8 @@ int main(int argc, char **argv)
                          tmp_path, test_logfile_lock);
 
     rc = g_test_run();
+    qemu_log_close();
+    drain_call_rcu();
 
     rmdir_full(tmp_path);
     return rc;