Bundle MinGw runtime into Windows android installers

Required by host tools.

Change-Id: I00a6f61925390f9d907d2b59000dbab77f958dac
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>