title: Qt deploy cannot find Visual Studio installation directory
body: <p>I'm having a problem with Qt Deployment:</p>
  <p>After a windeployqt App.exe, it returns</p>
  <pre><code>Adding Qt5Svg for qsvgicond.dll
  Direct dependencies: Qt5Core Qt5Gui Qt5SerialPort Qt5Widgets
  All dependencies   : Qt5Core Qt5Gui Qt5SerialPort Qt5Widgets
  To be deployed     : Qt5Core Qt5Gui Qt5SerialPort Qt5Svg Qt5Widgets
  Warning: Cannot find Visual Studio installation directory, VCINSTALLDIR is not set.
  </code></pre>
  <p>(I have to use the Qt 5.12.2 (MSVC 2017 64-bit) console, in the windows powershell the command windeployqt isn't found).</p>
  <p>It doesn't deploy the msvc dll. How can I set VCINSTALLDIR?</p>
  <p>Someone can help me?
  Thanks a lot</p>