Intruduced server_state::interrupt_state_waiters() to interrupt
all waiters inside server_state::wait_until_state(). This mechanism
is needed when an error is encountered during state change processing
and waiting threads may need to be interrupted to check and handle
the error condition.
Made server_state::wait_until_state() to throw exception if the
wait was interrupted and the new server state is either disconnecting
or disconnected, which usually indicates error condition.
e9bb552096