windows: fix handle leak on EMFILE

If CreateFileW succeeds, but _open_osfhandle fails, the handle must be closed.

PR-URL: https://github.com/libuv/libuv/pull/278
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

src/win/fs.c

@@ -511,6 +511,7 @@ void fs__open(uv_fs_t* req) {
       SET_REQ_WIN32_ERROR(req, GetLastError());
     else
       SET_REQ_WIN32_ERROR(req, UV_UNKNOWN);
+    CloseHandle(file);
     return;
   }