Quelque chose

checking if UIC has KDE plugins available... no
configure: error:
you need to install kdelibs first.

If you did install kdelibs, then the Qt version that is picked up by
this configure is not the same version you used to compile kdelibs.
The Qt Plugin installed by kdelibs is *ONLY* loadable if it is the
_same Qt version_, compiled with the _same compiler_ and the same Qt
configuration settings.