fix warning for MinGW
fix warning for MinGW

The following warning was given for each file:
[-fPIC ignored for target (all code is position independent)]

Change-Id: Icba7ce3571f5fb75f4d6cc3d5df8d80777d402b0
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@nokia.com>

Distrotech/qbs,qt-labs/qbs,qt-labs/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,Distrotech/qbs,villytiger/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,Distrotech/qbs,Distrotech/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,Distrotech/qbs,gatzka/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,villytiger/qbs,villytiger/qbs,Distrotech/qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs