tks Predrag and Thomas. That is it: the jre readme file has all the necessary information. so, Jre is solved but libreoffice installation still fails even after ports -u, as pastebin below shows:
You may notice that it is trying to update the libreoffice from the 'swhitton' repository, not the contrib repository. The contrib repository is the one that got the update. You will want to visit the ordering of your prtdir entries in /etc/prt-get.conf to ensure contrib is higher than swhitton.