Remove fuchsia references as it is not supported. (#355)

src/reactor/poll_evented.rs

@@ -428,7 +428,7 @@ fn usize2ready(bits: usize) -> Ready {
     ready | platform::usize2ready(bits)
 }
 
-#[cfg(all(unix, not(target_os = "fuchsia")))]
+#[cfg(unix)]
 mod platform {
     use mio::Ready;
     use mio::unix::UnixReady;
@@ -516,7 +516,7 @@ mod platform {
     }
 }
 
-#[cfg(any(windows, target_os = "fuchsia"))]
+#[cfg(windows)]
 mod platform {
     use mio::Ready;