don't hang in .qmake.cache search when build dir does not exist
don't hang in .qmake.cache search when build dir does not exist

QDir::cdUp() is strange ...

xianian/qt-creator,duythanhphan/qt-creator,bakaiadam/collaborative_qt_creator,syntheticpp/qt-creator,kuba1/qtcreator,darksylinc/qt-creator,pcacjr/qt-creator,omniacreator/qtcreator,kuba1/qtcreator,duythanhphan/qt-creator,KDE/android-qt-creator,martyone/sailfish-qtcreator,colede/qtcreator,renatofilho/QtCreator,yinyunqiao/qtcreator,dmik/qt-creator-os2,darksylinc/qt-creator,AltarBeastiful/qt-creator,omniacreator/qtcreator,kuba1/qtcreator,pcacjr/qt-creator,richardmg/qtcreator,martyone/sailfish-qtcreator,darksylinc/qt-creator,bakaiadam/collaborative_qt_creator,KDE/android-qt-creator,syntheticpp/qt-creator,pcacjr/qt-creator,KDE/android-qt-creator,omniacreator/qtcreator,richardmg/qtcreator,KDE/android-qt-creator,maui-packages/qt-creator,darksylinc/qt-creator,farseerri/git_code,yinyunqiao/qtcreator,azat/qtcreator,malikcjm/qtcreator,KDAB/KDAB-Creator,martyone/sailfish-qtcreator,bakaiadam/collaborative_qt_creator,omniacreator/qtcreator,danimo/qt-creator,xianian/qt-creator,azat/qtcreator,duythanhphan/qt-creator,colede/qtcreator,xianian/qt-creator,colede/qtcreator,yinyunqiao/qtcreator,duythanhphan/qt-creator,sandsmark/qtcreator-minimap,hdweiss/qt-creator-visualizer,enricoros/k-qt-creator-inspector,sandsmark/qtcreator-minimap,hdweiss/qt-creator-visualizer,amyvmiwei/qt-creator,xianian/qt-creator,maui-packages/qt-creator,xianian/qt-creator,renatofilho/QtCreator,farseerri/git_code,farseerri/git_code,amyvmiwei/qt-creator,omniacreator/qtcreator,KDE/android-qt-creator,farseerri/git_code,danimo/qt-creator,duythanhphan/qt-creator,hdweiss/qt-creator-visualizer,AltarBeastiful/qt-creator,maui-packages/qt-creator,dmik/qt-creator-os2,danimo/qt-creator,bakaiadam/collaborative_qt_creator,colede/qtcreator,Distrotech/qtcreator,azat/qtcreator,kuba1/qtcreator,omniacreator/qtcreator,xianian/qt-creator,Distrotech/qtcreator,amyvmiwei/qt-creator,kuba1/qtcreator,KDAB/KDAB-Creator,jonnor/qt-creator,kuba1/qtcreator,pcacjr/qt-creator,martyone/sailfish-qtcreator,Distrotech/qtcreator,KDE/android-qt-creator,jonnor/qt-creator,Distrotech/qtcreator,AltarBeastiful/qt-creator,KDAB/KDAB-Creator,dmik/qt-creator-os2,KDE/android-qt-creator,dmik/qt-creator-os2,syntheticpp/qt-creator,ostash/qt-creator-i18n-uk,richardmg/qtcreator,farseerri/git_code,renatofilho/QtCreator,pcacjr/qt-creator,xianian/qt-creator,farseerri/git_code,richardmg/qtcreator,yinyunqiao/qtcreator,danimo/qt-creator,dmik/qt-creator-os2,amyvmiwei/qt-creator,amyvmiwei/qt-creator,KDAB/KDAB-Creator,danimo/qt-creator,Distrotech/qtcreator,Distrotech/qtcreator,maui-packages/qt-creator,AltarBeastiful/qt-creator,syntheticpp/qt-creator,malikcjm/qtcreator,AltarBeastiful/qt-creator,enricoros/k-qt-creator-inspector,malikcjm/qtcreator,hdweiss/qt-creator-visualizer,AltarBeastiful/qt-creator,jonnor/qt-creator,maui-packages/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,farseerri/git_code,ostash/qt-creator-i18n-uk,yinyunqiao/qtcreator,dmik/qt-creator-os2,darksylinc/qt-creator,martyone/sailfish-qtcreator,renatofilho/QtCreator,kuba1/qtcreator,darksylinc/qt-creator,danimo/qt-creator,omniacreator/qtcreator,xianian/qt-creator,KDAB/KDAB-Creator,richardmg/qtcreator,kuba1/qtcreator,richardmg/qtcreator,enricoros/k-qt-creator-inspector,amyvmiwei/qt-creator,syntheticpp/qt-creator,enricoros/k-qt-creator-inspector,colede/qtcreator,duythanhphan/qt-creator,malikcjm/qtcreator,ostash/qt-creator-i18n-uk,martyone/sailfish-qtcreator,azat/qtcreator,sandsmark/qtcreator-minimap,ostash/qt-creator-i18n-uk,amyvmiwei/qt-creator,darksylinc/qt-creator,ostash/qt-creator-i18n-uk,bakaiadam/collaborative_qt_creator,farseerri/git_code,jonnor/qt-creator,hdweiss/qt-creator-visualizer,azat/qtcreator,malikcjm/qtcreator,syntheticpp/qt-creator,AltarBeastiful/qt-creator,maui-packages/qt-creator,sandsmark/qtcreator-minimap,jonnor/qt-creator,duythanhphan/qt-creator,sandsmark/qtcreator-minimap,malikcjm/qtcreator,pcacjr/qt-creator,enricoros/k-qt-creator-inspector,bakaiadam/collaborative_qt_creator,kuba1/qtcreator,malikcjm/qtcreator,enricoros/k-qt-creator-inspector,amyvmiwei/qt-creator,jonnor/qt-creator,dmik/qt-creator-os2,bakaiadam/collaborative_qt_creator,martyone/sailfish-qtcreator,renatofilho/QtCreator,yinyunqiao/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,KDE/android-qt-creator,enricoros/k-qt-creator-inspector,ostash/qt-creator-i18n-uk,syntheticpp/qt-creator,KDAB/KDAB-Creator,pcacjr/qt-creator,renatofilho/QtCreator,sandsmark/qtcreator-minimap,colede/qtcreator,azat/qtcreator,Distrotech/qtcreator,xianian/qt-creator,richardmg/qtcreator,hdweiss/qt-creator-visualizer,danimo/qt-creator,colede/qtcreator,maui-packages/qt-creator,ostash/qt-creator-i18n-uk,yinyunqiao/qtcreator,AltarBeastiful/qt-creator,darksylinc/qt-creator