Fixing bug in ClassHierarchy.getLeastCommonSuperclass

If C1 extends C2 extends C3 getLeastCommonSuperClass(C1,C2) would give C3 instead of C2

com.ibm.wala.core/src/com/ibm/wala/ipa/cha/ClassHierarchy.java

@@ -769,7 +769,7 @@ public class ClassHierarchy implements IClassHierarchy {
       }
       IClass aa = a;
       while (aa != null) {
-        if (superB.contains(aa)) {
+        if (b.equals(aa) || superB.contains(aa)) {
           return aa;
         }
         aa = aa.getSuperclass();