patch 8.1.1981: the evalfunc.c file is too big

Problem:    The evalfunc.c file is too big.
Solution:   Move undo functions to undo.c.  Move cmdline functions to
            ex_getln.c.  Move some container functions to list.c.

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1981,
 /**/
     1980,
 /**/