added lemma about irreflexivity of pointer inequality in Imperative_HOL
added lemma about irreflexivity of pointer inequality in Imperative_HOL

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