I just checked - the python-build-system doesn't allow passing flags when
invoking setup.py . That's the only reason the custom build phase is there...
Also, I think we should adapt wxwidgets to add propagated-inputs.
Because the wxwidgets header files include opengl and gtk header files, a
client using wxwidgets really requires gtk. However, the entire point of wx* is
to have platform independent API - I don't think that the client package should
include gtk or mesa for example. It should just include wxwidgets and that's it.