node: ensure that streams2 won't .end() stdin

Stdin is purely read-only stream. Although, `net.Socket` might be used
to create it if stdin is in fact a Pipe or TCP socket, the
`stream.Duplex` should not try to call `.end()` on it.

Fix: #1068
PR-URL: #1233
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>

Author: indutny

src/node.js

@@ -630,6 +630,8 @@
               writable: false
             });
           }
+          // Make sure the stdin can't be `.end()`-ed
+          stdin._writableState.ended = true;
           break;
 
         default: