libwps depends on app-doc/doxygen[-nodot] (if USE=doc). Recent versions of doxygen have a dot USE flag, not a nodot USE flag. Please change the dependency to something like "|| ( <app-doc/doxygen-1.7.6.1[-nodot] >=app-doc/doxygen-1.7.6.1[dot] )" so libwps[doc] and >=doxygen-1.7.6.1 can be installed on the same system.
Actually it is easier, it does not need the nodot check. So I removed it. :)