add Arrays test for equals and hashCode, handle corner cases with null

classpath/java/util/Arrays.java

@@ -43,15 +43,25 @@ public class Arrays {
   }
 
   public static int hashCode(Object[] array) {
+    if(array == null) {
+      return 9023;
+    }
+
     int hc = 823347;
     for(Object o : array) {
-      hc += o.hashCode();
+      hc += o != null ? o.hashCode() : 54267;
       hc *= 3;
     }
     return hc;
   }
 
   public static boolean equals(Object[] a, Object[] b) {
+    if(a == b) {
+      return true;
+    }
+    if(a == null || b == null) {
+      return false;
+    }
     if(a.length != b.length) {
       return false;
     }