patch 8.1.1989: the evalfunc.c file is still too big

Problem:    The evalfunc.c file is still too big.
Solution:   Move f_pathshorten() to filepath.c.  Move f_cscope_connection() to
            if_cscope.c.  Move diff_ functions to diff.c.  Move timer_
            functions to ex_cmds2.c.  move callback functions to evalvars.c.

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1989,
 /**/
     1988,
 /**/