Warn if the update info plugin is useless.
Warn if the update info plugin is useless.

This usually happens if somebody enables it manually outside
of an SDK context.

Change-Id: I3ad37edc9d682ca1416ab594b959b8e4d5eb6041
Reviewed-by: Eike Ziller <c142da16c73a95a82d35191bcc55b22835617128@nokia.com>

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