Restore datagram connect test

Author: Berrysoft

library/std/src/os/unix/net/tests.rs

@@ -308,7 +308,6 @@ fn test_unnamed_unix_datagram() {
 
 #[test]
 #[cfg_attr(target_os = "android", ignore)] // Android SELinux rules prevent creating Unix sockets
-#[cfg_attr(target_os = "cygwin", ignore)] // Cygwin fails to determine the addr type from recvfrom
 fn test_unix_datagram_connect_to_recv_addr() {
     let dir = tmpdir();
     let path1 = dir.path().join("sock1");