patch 8.0.1398: :packadd does not load packages from the "start" directory

Problem:    :packadd does not load packages from the "start" directory.
            (Alejandro Hernandez)
Solution:   Make :packadd look in the "start" directory if those packages were
            not loaded on startup.
diff --git a/src/version.c b/src/version.c
index 096d21c..2580b9e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1398,
+/**/
     1397,
 /**/
     1396,