Don't create a QProcess object every second.

Creating a QProcess every second is very VERY expensive, making the QtCreator UI
experience pretty bad, the UI was not responsive when debugging or even when
running an Android application from QtCreator.

Thanks to Intel's VTUNE I could spot and fix the problem in minutes.

Change-Id: I6d3dc71db93e91d9846101a1877bab017df41aba
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>