Early exit from QRegion::intersects() if there is only one rect.
Early exit from QRegion::intersects() if there is only one rect.

Don't waste cycles with constructing two vectors with rectangles if
there is only one rectangle in each of the two regions.

Reviewed-by: Lars
Reviewed-by: bnilsen

radekp/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,radekp/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,radekp/qt,igor-sfdc/qt-wk,radekp/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,radekp/qt,radekp/qt,radekp/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt