Fix linking error on make install.
Fix linking error on make install.

The loaders were installed before libpeasui, hence it failed as the
python bindings are now also linking against libpeasui.

GNOME/libpeas,chergert/libpeas,Distrotech/libpeas,Distrotech/libpeas,chergert/libpeas,gregier/libpeas,gregier/libpeas,Distrotech/libpeas,gregier/libpeas,GNOME/libpeas,gregier/libpeas,chergert/libpeas