patch 9.0.0948: 'ttyfast' is set for arbitrary terminals

Problem:    'ttyfast' is set for arbitrary terminals.
Solution:   Always set 'ttyfast'. (closes #11549)
diff --git a/src/optiondefs.h b/src/optiondefs.h
index 0278b60..e7eb357 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -2599,7 +2599,7 @@
 			    {(char_u *)TRUE, (char_u *)0L} SCTX_INIT},
     {"ttyfast",	    "tf",   P_BOOL|P_NO_MKRC|P_VI_DEF,
 			    (char_u *)&p_tf, PV_NONE,
-			    {(char_u *)FALSE, (char_u *)0L} SCTX_INIT},
+			    {(char_u *)TRUE, (char_u *)0L} SCTX_INIT},
     {"ttymouse",    "ttym", P_STRING|P_NODEFAULT|P_NO_MKRC|P_VI_DEF,
 #if defined(UNIX) || defined(VMS)
 			    (char_u *)&p_ttym, PV_NONE,