<dbus-0.90 has been removed from the tree. So you need to keyword >=dev-libs/dbus-glib-0.71, meanwhile, i had to drop your keyword from xchat. Feel free to readd your keyword, or close this bug. Thanks.
Well, apparently none of MIPS devs cares enough about dbus. Since it's a use flag for XChat, I use-masked, and restored MIPS keywords.