Fix the judgment of absolute path on Windows
Fix the judgment of absolute path on Windows

e.g.
D:/absolute/path/test.lib
or:
c:\\absolute\\path\\test.lib

Change-Id: If58a57acf05d63139c5ebad078cee3671fe361e5
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@nokia.com>

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