title: Converting steady_clock::time_point to time_t
body: <p>I'm using the <code>steady_clock</code> for saving the time stamp of some messages. For debug purpose is usefull to have the calendar (or something similar).</p>
  
  <p>For other clocks ther's the static function <code>to_time_t</code>, but on GCC (MinGW 4.8.0) this function is not present.</p>
  
  <p>Now i print something like:</p>
  
  <pre><code>Timestamp: 26735259098242
  </code></pre>
  
  <p>For timestamp i need a steady_clock so I cannot use <code>system_clock</code> or others.</p>
  
  <p><b> Edit </b>
  The previous print is given from the <code>time_since_epoch().count</code>()</p>