[build] remove xlint -unused, not understood by scala 2.11 (#9551)
[build] remove xlint -unused, not understood by scala 2.11 (#9551)


danking/hail,cseed/hail,hail-is/hail,hail-is/hail,hail-is/hail,cseed/hail,cseed/hail,danking/hail,hail-is/hail,cseed/hail,hail-is/hail,danking/hail,danking/hail,cseed/hail,hail-is/hail,danking/hail,danking/hail,hail-is/hail,cseed/hail,danking/hail,hail-is/hail,cseed/hail,danking/hail,cseed/hail