patch 8.0.1389: getqflist() items are missing if not set

Problem:    getqflist() items are missing if not set, that makes it more
            difficult to handle the values.
Solution:   When a value is not available return zero or another invalid
            value. (Yegappan Lakshmanan, closes #2430)

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1389,
 /**/
     1388,
 /**/