patch 8.0.1618: color Grey50 is missing in the compiled-in table

Problem:    Color Grey50, used for ToolbarLine, is missing in the compiled-in
            table.
Solution:   Add the color to the list. (Kazunobu Kuriyama)
diff --git a/src/version.c b/src/version.c
index 92ca63a..35feb76 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1618,
+/**/
     1617,
 /**/
     1616,