title: error: 'std::this_thread' has not been declared
body: <p>I try to use std::this_thread::sleep_for() function but got the error<br>
  <code>error: 'std::this_thread' has not been declared</code>.<br>
  The flag _GLIBCXX_USE_NANOSLEEP included.<br>
  What else is needed to force it to work?<br>
  MinGW ==> gcc version 4.7.2 (GCC)  </p>
  
  <p>SSCCE:  </p>
  
  <pre><code>#include&lt;thread&gt;
  
  int main() {
    std::this_thread::sleep_for(std::chrono::seconds(3));
  }
  </code></pre>
  
  <p>command line:  </p>
  
  <pre><code>g++ -D_GLIBCXX_USE_NANOSLEEP -std=gnu++0x ssce.cpp -o ssce.exe
  </code></pre>
  
  <p>result of compilation:  </p>
  
  <pre><code>ssce.cpp: In function 'int main()':
  ssce.cpp:4:8: error: 'std::this_thread' has not been declared
  </code></pre>