remove special cases for CVC4 that are actually unused (see also 6273d4c8325b and 1f1c5d85d232);

rebuild cvc5 component (still inactive); more robust workaround on all platforms, avoid crash of "sledgehammer [cvc5]" seen on x86_64-linux after line 75 of "$AFP/thys/Boolos_Curious_Inference_Automated/Boolos_Curious_Inference_Automated.thy";