patch 9.1.1181: Unnecessary STRLEN() calls in insexpand.c

Problem:  Unnecessary STRLEN() calls in insexpand.c (after 9.1.1178).
Solution: Use the already available length (zeertzjq).

closes: #16814

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1181,
 /**/
     1180,
 /**/