title: unresolved linker errors for many windows functions in Qt
body: <p>In Qt, I am getting unresolved linker errors for many windows functions such as <code>SHGetKnownFolderPath</code></p>
  
  <pre><code>#include "pip.h"
  #include "ui_pip.h"
  #include &lt;QFileDialog&gt;
  #include &lt;QMessageBox&gt;
  #include &lt;Objbase.h&gt;
  #include &lt;iostream&gt;
  #include &lt;fstream&gt;
  #include &lt;string&gt;
  #include &lt;sstream&gt;
  #include &lt;algorithm&gt;
  #include &lt;QtNetwork/QHostAddress&gt;
  #include &lt;shlobj.h&gt;
  #include &lt;windows.h&gt;
  #include &lt;Shlwapi.h&gt;
  #include &lt;Knownfolders.h&gt;
  </code></pre>
  
  <p>Function:</p>
  
  <pre><code>PWSTR appData = 0;
  
      if (SUCCEEDED(SHGetKnownFolderPath(FOLDERID_Desktop,
                                     0,
                                     NULL,
                                     &amp;appData)))
  {
      wcout &lt;&lt; appData &lt;&lt; endl;
  }
  </code></pre>
  
  <p>Linker Error:</p>
  
  <pre><code>pip.obj : error LNK2019: unresolved external symbol _SHGetKnownFolderPath@16 
  referenced in function "private: void __thiscall pip::on_submitButton_clicked(void)" 
  (?on_submitButton_clicked@pip@@AAEXXZ)
  </code></pre>
  
  <p>Do I need to tell QT where the <code>Shell32.dll</code> library is or something for <code>shlobj.h</code>?</p>