TS-977: Fix RecMessageSend regression

After removing the static g_mode_type variable from RecMessage.cc file
by previous commit: 3321de50, traffic_manager will crash when boot.

The root cause is that RecMessageSend() will be called before lmgmt has
been initialized.

We can simply check g_message_initialized instead of g_mode_type to
decide whether RecMessageSend() could be executed safely.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
Signed-off-by: Zhao Yongming <ming.zym@gmail.com>