Move stderr of stty to pipe

If stderr is left as its default value, any error messages arising from
stty are output to the stderr of the program calling `size`, causing
strange messages if stty fails.

src/System/Console/Terminal/Windows.hs

@@ -42,6 +42,7 @@ size = do
                 let stty = (shell "stty size") {
                       std_in  = UseHandle stdin
                     , std_out = CreatePipe
+                    , std_err = CreatePipe
                     }
                 (_, mbStdout, _, rStty) <- createProcess stty
                 exStty <- waitForProcess rStty