title: QTextDocument print to pdf and unicode
body: <p>I try to print pdf file from QTextDocument. Content of document is set by setHtml(). 
  Simplified example:</p>
  
  <pre><code>QTextDocument document;
  document.setHtml("&lt;h1&gt;My html \304\205&lt;/h1&gt;"); // Octal encoded ą
  
  QPrinter printer(QPrinter::HighResolution);
  printer.setPageSize(QPrinter::A4);
  printer.setOutputFormat(QPrinter::PdfFormat);
  
  printer.setOutputFileName("cert.pdf");
  document.print(&amp;printer);
  </code></pre>
  
  <p>It does not work as expected on windows (msvc). I get pdf file with "?" in place of most polish characters. It works on ubuntu. </p>
  
  <p>On windows It makes pdf with tahoma font embedded subset. How to force QPrinter or QPrintEngine to embed more characters from this (or any other) font?</p>