patch 8.2.2508: cannot change the character displayed in non existing lines

Problem:    Cannot change the character displayed in non existing lines.
Solution:   Add the "eob" item to 'fillchars'. (closes #7832, closes #3820)
diff --git a/src/globals.h b/src/globals.h
index 4daa092..3ad4227 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1363,6 +1363,7 @@
 EXTERN int	fill_vert INIT(= ' ');
 EXTERN int	fill_fold INIT(= '-');
 EXTERN int	fill_diff INIT(= '-');
+EXTERN int	fill_eob INIT(= '~');
 
 #ifdef FEAT_FOLDING
 EXTERN int	disable_fold_update INIT(= 0);