Add a debugging statement to hopefully figure out why the test fails on

OSX.

Author: asomers

test/sys/test_aio.rs

@@ -84,6 +84,7 @@ fn test_fsync() {
                             0,   //priority
                             SigevNotify::SigevNone);
     let err = aiocb.fsync(AioFsyncMode::O_SYNC);
+    println!("fsync returned {:?}", err);   //why does if fail on OSX?
     assert!(err.is_ok());
     poll_aio(&mut aiocb).unwrap();
     aiocb.aio_return().unwrap();