razorqt-base/libqtxdg: version bump, remove lxqt-base/libqtxdg

Please, review razorqt-base/libqtxdg. Other ebuilds were changed only because of dependency on it. I'll address them later, so, please, do not report their qa issues here.

@Pesa: concerning you question about my commit permisions here -- I do not have them as I'm not a member of qt herd and have not asked for it. Anyway I want a review from somebody (otherwise I'd just commit it directly to the tree :-b). Btw, thanks you for your work. )