title: Code with codecvt fails to link
body: <p>Using the latest Visual Studio Community Preview (15.6.0 Preview 2), the following code fails to link:</p>
  
  <pre><code>#include &lt;locale&gt;
  
  int main()
  {
      std::locale loc;
      auto const&amp; cvt = std::use_facet&lt;std::codecvt&lt;char32_t, char, std::mbstate_t&gt;&gt;(loc);
  }
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>error LNK2001: unresolved external symbol "public: static class std::locale::id std::codecvt&lt;char32_t,char,struct _Mbstatet&gt;::id" (?id@?$codecvt@_UDU_Mbstatet@@@std@@2V0locale@2@A)
  </code></pre>
  
  <p>I've heard that this may be due to Visual C++ bug.  Can anyone suggest a workaround?</p>