It would appear that ICU 51.2 causes segfaults in at least LibreOffice:
I moved the poppler rebuilds out of testing so that libreoffice doesn't have to be rebuilt twice. I will proceed to rebuild libreoffice, verify that the segfaults are gone and push it to extra.
I assume that only packages linking to the layout engine (libicule.so.51) need to be rebuilt, so I will only do libreoffice and harfbuzz. (I'm basing this on the upstream-tracker.org report which shows just a few symbols in the LayoutEngine class as affected.)
Andy, please check to see if anything else needs to be done to address this problem. :)