std::rt::uv::uvio: Enable tests on Win32

Closes #8816.

src/libstd/rt/uv/uvio.rs

@@ -1740,7 +1740,6 @@ fn test_read_read_read() {
 }
 
 #[test]
-#[ignore(cfg(windows))] // FIXME #8816
 fn test_udp_twice() {
     do run_in_mt_newsched_task {
         let server_addr = next_test_ip4();
@@ -1892,7 +1891,6 @@ fn file_test_uvio_full_simple_impl() {
 }
 
 #[test]
-#[ignore(cfg(windows))] // FIXME #8816
 fn file_test_uvio_full_simple() {
     do run_in_mt_newsched_task {
         file_test_uvio_full_simple_impl();