Properly wait for server in TestThriftServerCmdLine

In 0.94 I find:
Threads.sleepWithoutInterrupt(2000)

In trunk I see:

     while ( thriftServer.serverRunner == null || thriftServer.serverRunner.tserver == null ){
       Thread.sleep(1);
     }

Both aren't good.
The 0.94 version will fail if the server does not come up within 2s. The trunk version (1) might wait forever and cause a long timeout for the test and (2) wait quite busily with only 1ms of sleeping.