C++: fixed source-to-project-part map calculation
C++: fixed source-to-project-part map calculation

When the information for a project is updated, the mapping was cleared
and only recalculated for the new project info. Thereby wiping out
the info for any previously added project.

Change-Id: Ic6999b9be07f8cb6b4638723e6c8c7d2d3ca52e7
Reviewed-by: Erik Verbruggen <5edfe905d082749f2ac3f4e6b42937f39f083771@nokia.com>

jonnor/qt-creator,maui-packages/qt-creator,syntheticpp/qt-creator,richardmg/qtcreator,darksylinc/qt-creator,amyvmiwei/qt-creator,farseerri/git_code,kuba1/qtcreator,martyone/sailfish-qtcreator,azat/qtcreator,richardmg/qtcreator,AltarBeastiful/qt-creator,darksylinc/qt-creator,Distrotech/qtcreator,farseerri/git_code,martyone/sailfish-qtcreator,omniacreator/qtcreator,martyone/sailfish-qtcreator,KDAB/KDAB-Creator,farseerri/git_code,xianian/qt-creator,duythanhphan/qt-creator,ostash/qt-creator-i18n-uk,colede/qtcreator,farseerri/git_code,kuba1/qtcreator,syntheticpp/qt-creator,danimo/qt-creator,maui-packages/qt-creator,farseerri/git_code,omniacreator/qtcreator,ostash/qt-creator-i18n-uk,xianian/qt-creator,Distrotech/qtcreator,KDE/android-qt-creator,richardmg/qtcreator,syntheticpp/qt-creator,omniacreator/qtcreator,Distrotech/qtcreator,jonnor/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,danimo/qt-creator,KDE/android-qt-creator,darksylinc/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,kuba1/qtcreator,KDE/android-qt-creator,AltarBeastiful/qt-creator,Distrotech/qtcreator,AltarBeastiful/qt-creator,syntheticpp/qt-creator,maui-packages/qt-creator,martyone/sailfish-qtcreator,hdweiss/qt-creator-visualizer,maui-packages/qt-creator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,malikcjm/qtcreator,xianian/qt-creator,xianian/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,danimo/qt-creator,amyvmiwei/qt-creator,jonnor/qt-creator,darksylinc/qt-creator,KDAB/KDAB-Creator,azat/qtcreator,duythanhphan/qt-creator,farseerri/git_code,malikcjm/qtcreator,darksylinc/qt-creator,darksylinc/qt-creator,danimo/qt-creator,Distrotech/qtcreator,xianian/qt-creator,kuba1/qtcreator,danimo/qt-creator,duythanhphan/qt-creator,danimo/qt-creator,Distrotech/qtcreator,kuba1/qtcreator,jonnor/qt-creator,kuba1/qtcreator,kuba1/qtcreator,duythanhphan/qt-creator,ostash/qt-creator-i18n-uk,danimo/qt-creator,ostash/qt-creator-i18n-uk,darksylinc/qt-creator,hdweiss/qt-creator-visualizer,KDAB/KDAB-Creator,azat/qtcreator,colede/qtcreator,omniacreator/qtcreator,darksylinc/qt-creator,malikcjm/qtcreator,hdweiss/qt-creator-visualizer,KDAB/KDAB-Creator,KDE/android-qt-creator,omniacreator/qtcreator,KDE/android-qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,farseerri/git_code,colede/qtcreator,martyone/sailfish-qtcreator,kuba1/qtcreator,richardmg/qtcreator,syntheticpp/qt-creator,hdweiss/qt-creator-visualizer,ostash/qt-creator-i18n-uk,Distrotech/qtcreator,hdweiss/qt-creator-visualizer,omniacreator/qtcreator,richardmg/qtcreator,maui-packages/qt-creator,azat/qtcreator,maui-packages/qt-creator,KDE/android-qt-creator,KDAB/KDAB-Creator,AltarBeastiful/qt-creator,malikcjm/qtcreator,AltarBeastiful/qt-creator,KDE/android-qt-creator,jonnor/qt-creator,colede/qtcreator,richardmg/qtcreator,AltarBeastiful/qt-creator,danimo/qt-creator,amyvmiwei/qt-creator,colede/qtcreator,azat/qtcreator,omniacreator/qtcreator,malikcjm/qtcreator,jonnor/qt-creator,azat/qtcreator,KDAB/KDAB-Creator,duythanhphan/qt-creator,danimo/qt-creator,maui-packages/qt-creator,malikcjm/qtcreator,malikcjm/qtcreator,ostash/qt-creator-i18n-uk,farseerri/git_code,ostash/qt-creator-i18n-uk,colede/qtcreator,hdweiss/qt-creator-visualizer,syntheticpp/qt-creator,amyvmiwei/qt-creator,richardmg/qtcreator,duythanhphan/qt-creator,AltarBeastiful/qt-creator,syntheticpp/qt-creator,colede/qtcreator,amyvmiwei/qt-creator,xianian/qt-creator,duythanhphan/qt-creator,KDE/android-qt-creator,kuba1/qtcreator,martyone/sailfish-qtcreator