Bug2235

Fixes https://github.com/kripken/emscripten/issues/2235

```
➜  tests git:(incoming) ✗ python runner.py test_fs_emptyPath
test_fs_emptyPath (test_core.default) ... (checking sanity from test runner)
INFO     root: (Emscripten: Running sanity checks)
WARNING  root: function requested to be exported, but not implemented: "_malloc"
ok

----------------------------------------------------------------------
Ran 1 test in 0.788s

OK
```