Similar to bug 368787, strigi needs boost for building, but not for running. Nothing is linked to it, after removing boost kde session works fine, revdep-rebuild does not find any problem. https://bugs.gentoo.org/show_bug.cgi?id=384519#c4 is not correct.
Thanks for reporting. Fixed in =app-misc/strigi-0.7.6-r1 and =app-misc/strigi-0.7.7. Sync in some hours.