Make sure janus_session lock is obtained first and websocket_conn lock
second, in order to prevent a possible deadlock.
Change-Id: I3db1d5cea0c0295cc10c71edd20c86ce054f520b
Warned-by: Coverity
This isn't really necessary as at this point the janus_session object is
private to the thread, but we add the locking anyway to silence the
warning.
Warned-by: Coverity
Change-Id: I0b192f2f5827ad917cf5110ce486fc6cd49e1a71