explanation: via the unresolved problems with the hig-level model,
probably a dependency to AssetManager and from there to the core systems
"bubbled" into the liblumiera.so, forcing us to link these things for now
don't link the tests with -ldl
Renamed GTK_LUMIERA_* to LUMIERA_GUI_* and include all gui relevant config
results here.
Set it explicit, don't add the results to CFLAGS or LIBS, the default
behaviour linked all LIBS in, even in plugins, that was not intended.
this prevents strange (_CPPFLAGS) dependencies such as the one that was identified and fixed in admin/Makefile.am
Also, make sure to include the global $(AM_CPPFLAGS) flags in the per-target ones
