These packages make use of gtk3 useflag which indicates that there are issues of migration to gtk+:3.
Gtk3 and similar useflags should be avoided.
Adding to tracker. Please have a look.
*librsvg-2.36.0 (12 Apr 2012)
12 Apr 2012; Alexandre Rostovtsev <email@example.com>
Version bump with numerous bugfixes. Deprecated /usr/bin/rsvg utility was
removed. The rsvg-view-3 utility is now built only when USE="gtk tools".