virtual/gnustep-back is defined in eclass/gnustep.eclass, but there isnt an entry in /usr/portage/profiles/gcc34-x86-2004.2/virtuals, therefore ebuilds like gmines are failing because they cant find the default package to satisfy virtuals/gnustep-back
Virtual for that profile added. ... however, maybe you should consider updating to a newer profile anyway, if you can? Just fyi...