Clean up the ProjectGenerator interface
Clean up the ProjectGenerator interface

Make the virtual generate() function private; it is only supposed to be
called from within this class. Merge the two "private:" sections while
we're at it.

Change-Id: I43dbd5d45e8c5d803f1bfbf088dbe1944a59c05b
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@qt.io>

qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs