Corrected [-hash] implementations.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@3123 72102866-910b-0410-8b05-ffd578937521

Source/NSSet.m

@@ -328,6 +328,11 @@ static Class NSMutableSet_concrete_class;
   return (([self member:anObject]) ? YES : NO);
 }
 
+- (unsigned) hash
+{
+    return [self count];
+}
+
 - (void) makeObjectsPerform: (SEL)aSelector
 {
   id o, e = [self objectEnumerator];