Bug 630097 - (cov#15464) NULL dereference in repl code

If the attr parameter that is passed to my_ber_scanf_attr() is
NULL, we jump to the loser label where we clean up memory we may
have allocated.  We dereference attr without first checking if it
is NULL in this clean-up code.  We need to check if attr is NULL
before dereferencing it.

ldap/servers/plugins/replication/repl5_total.c

@@ -689,7 +689,7 @@ my_ber_scanf_attr (BerElement *ber, Slapi_Attr **attr, PRBool *deleted)
 
     return 0;
 loser:
-    if (*attr)
+    if (attr && *attr)
         slapi_attr_free (attr);
     if (value)
         slapi_value_free (&value);