* src/eltlparse/Makefile.am, src/kripkeparse/Makefile.am,
src/ltlparse/Makefile.am, src/neverparse/Makefile.am,
src/tgbaparse/Makefile.am: Use $(VISIBILITY_CXXFLAGS)
* src/eltlparse/public.hh, src/kripkeparse/public.hh,
src/ltlparse/ltlfile.hh, src/ltlparse/public.hh,
src/neverparse/public.hh, src/tgbaparse/public.hh:
Mark public symbols with SPOT_API.