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/optiondefs.h b/src/optiondefs.h
index 9961bd4..3e76c8a 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -952,7 +952,7 @@
 			    SCTX_INIT},
     {"fillchars",   "fcs",  P_STRING|P_VI_DEF|P_RALL|P_ONECOMMA|P_NODUP,
 			    (char_u *)&p_fcs, PV_NONE,
-			    {(char_u *)"vert:|,fold:-", (char_u *)0L}
+			    {(char_u *)"vert:|,fold:-,eob:~", (char_u *)0L}
 			    SCTX_INIT},
     {"fixendofline",  "fixeol", P_BOOL|P_VI_DEF|P_RSTAT,
 			    (char_u *)&p_fixeol, PV_FIXEOL,