Mac: No longer download and extract the separate qt_menu.nib

It is part of the installer framework now.

Change-Id: I151981146550221518fe5b0cc8f24de48ce2604b
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Qt Creator: build standalone installers for Win+Lin

Change-Id: I3fbed1d6756f46949c56163a6ea55e7635ba91e8
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>