Reenable test_fsync on OSX

test/sys/test_aio.rs

@@ -73,11 +73,8 @@ fn test_aio_cancel_all() {
     let _ = aiocb.aio_return();
 }
 
-// I can't explain why, but on Travis in OSX aiocb.fsync will repeatedly
-// return EAGAIN.  It doesn't happen on the bench.
 #[test]
-#[cfg_attr(any(target_os = "macos",
-               all(target_env = "musl", target_arch = "x86_64")), ignore)]
+#[cfg_attr(all(target_env = "musl", target_arch = "x86_64"), ignore)]
 fn test_fsync() {
     const INITIAL: &'static [u8] = b"abcdef123456";
     let mut f = tempfile().unwrap();
@@ -504,6 +501,8 @@ fn test_lio_listio_read_immutable() {
 }
 
 // Test dropping an AioCb that hasn't yet finished.
+// Skip on OSX where this test seems to hose the AIO subsystem and
+// causes subsequent tests to fail
 #[test]
 #[should_panic(expected = "Dropped an in-progress AioCb")]
 #[cfg(not(any(target_os = "macos", target_env = "musl")))]