patch 7.4.1553

Problem:    ":runtime" does not use 'packpath'.
Solution:   Add "what" argument.

src/version.c

@@ -743,6 +743,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1553,
 /**/
     1552,
 /**/