Upgrade the Windows deploy script to compile Qt

With that update, we will be able to ship the same Qt version on all platforms.
For the moment we are shipping one Qt version for GNU/Linux & macOs (4.12) and a different one for Windows (4.11.9).

This step is necesssary because there is no more prebuilded packages for Qt5, only sources are available. Also, the compilation steps are the same for Qt4 and Qt5.
This step will target Qt4. Wen switching to Qt5, we will only need to change the desired version, deploy scripts will work out-of-the-box.