Fix compilation with Qt 5 / nmake / shadow builds
Fix compilation with Qt 5 / nmake / shadow builds

qmake/qt4 included the source directory automatically for most plugins,
which got dropped in qt 5 (change 0f548b1744e2). Make sure it's
included again ...

Change-Id: Ief06cf9b3c7afd8432df7511df5f917023d477ef
Reviewed-by: Oswald Buddenhagen <6a8868beda3e139b5ac22b2534a23d3e6ba81819@nokia.com>
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@nokia.com>
Reviewed-by: Friedemann Kleint <1b9f2592239daaec4856ccc1cfb4d2d55b35fb71@nokia.com>

darksylinc/qt-creator,syntheticpp/qt-creator,colede/qtcreator,syntheticpp/qt-creator,martyone/sailfish-qtcreator,amyvmiwei/qt-creator,duythanhphan/qt-creator,farseerri/git_code,duythanhphan/qt-creator,colede/qtcreator,farseerri/git_code,farseerri/git_code,danimo/qt-creator,danimo/qt-creator,syntheticpp/qt-creator,amyvmiwei/qt-creator,richardmg/qtcreator,danimo/qt-creator,Distrotech/qtcreator,darksylinc/qt-creator,xianian/qt-creator,maui-packages/qt-creator,AltarBeastiful/qt-creator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,darksylinc/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,richardmg/qtcreator,farseerri/git_code,martyone/sailfish-qtcreator,Distrotech/qtcreator,AltarBeastiful/qt-creator,kuba1/qtcreator,xianian/qt-creator,colede/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,duythanhphan/qt-creator,syntheticpp/qt-creator,amyvmiwei/qt-creator,malikcjm/qtcreator,amyvmiwei/qt-creator,syntheticpp/qt-creator,duythanhphan/qt-creator,Distrotech/qtcreator,AltarBeastiful/qt-creator,malikcjm/qtcreator,Distrotech/qtcreator,Distrotech/qtcreator,xianian/qt-creator,kuba1/qtcreator,colede/qtcreator,richardmg/qtcreator,amyvmiwei/qt-creator,richardmg/qtcreator,omniacreator/qtcreator,richardmg/qtcreator,danimo/qt-creator,malikcjm/qtcreator,martyone/sailfish-qtcreator,malikcjm/qtcreator,kuba1/qtcreator,darksylinc/qt-creator,kuba1/qtcreator,syntheticpp/qt-creator,colede/qtcreator,xianian/qt-creator,maui-packages/qt-creator,kuba1/qtcreator,omniacreator/qtcreator,AltarBeastiful/qt-creator,amyvmiwei/qt-creator,syntheticpp/qt-creator,xianian/qt-creator,kuba1/qtcreator,martyone/sailfish-qtcreator,darksylinc/qt-creator,danimo/qt-creator,danimo/qt-creator,richardmg/qtcreator,malikcjm/qtcreator,malikcjm/qtcreator,AltarBeastiful/qt-creator,duythanhphan/qt-creator,omniacreator/qtcreator,danimo/qt-creator,maui-packages/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,darksylinc/qt-creator,duythanhphan/qt-creator,farseerri/git_code,malikcjm/qtcreator,colede/qtcreator,kuba1/qtcreator,Distrotech/qtcreator,maui-packages/qt-creator,kuba1/qtcreator,richardmg/qtcreator,xianian/qt-creator,omniacreator/qtcreator,colede/qtcreator,omniacreator/qtcreator,Distrotech/qtcreator,omniacreator/qtcreator,xianian/qt-creator,duythanhphan/qt-creator,danimo/qt-creator,farseerri/git_code,AltarBeastiful/qt-creator,omniacreator/qtcreator,maui-packages/qt-creator,darksylinc/qt-creator,maui-packages/qt-creator,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator,kuba1/qtcreator,darksylinc/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,farseerri/git_code,maui-packages/qt-creator