patch 9.1.1028: too many strlen() calls in screen.c

Problem:  too many strlen() calls in screen.c
Solution: refactor screen.c and remove calls to strlen(),
          verify that leadmultispace != NULL (John Marriott)

closes: #16460

Signed-off-by: John Marriott <basilisk@internode.on.net>
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 */
+/**/
+    1028,
 /**/
     1027,
 /**/