title: Error when im trying to convert cpp with std includes using Emscripten
body: <p>When i try to use emcc to convert the following code :</p>
  
  <pre><code>#include &lt;iostream&gt;
  int main()
  {
    std::cout &lt;&lt; "hello, world!" &lt;&lt; std::endl;
    return 0;
  }
  </code></pre>
  
  <p>I get this error : </p>
  
  <pre><code>Traceback (most recent call last):
    File "./emcc", line 797, in &lt;module&gt;
      extra_files_to_link.append(shared.Cache.get(name, create))
    File "/home/user/emscripten/tools/shared.py", line 879, in get
      shutil.copyfile(creator(), cachename)
    File "/usr/lib/python2.7/shutil.py", line 82, in copyfile
      with open(src, 'rb') as fsrc:
  IOError: [Errno 2] No such file or directory: '/tmp/emscripten_temp_MVh5qU/libcxx/libcxx.bc'
  </code></pre>
  
  <p>I can convert any source that dont use std.
  I can generate the bytecode of the example above using clang and execute with lli.</p>
  
  <p>I tried in two different machines(Linux 64) and had the same error.</p>
  
  <p>Can someone help me to avoid this error?</p>