fix IsaMakefile, removing mirabelle (not in HOL/ex/ROOT.ML anyway)
fix IsaMakefile, removing mirabelle (not in HOL/ex/ROOT.ML anyway)

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle