patch 8.1.1254: mapping completion contains dead code

Problem:    Mapping completion contains dead code.
Solution:   Remove the code.

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1254,
 /**/
     1253,
 /**/