patch 8.2.0774: t_TI and t_TE are output when using 'visualbell'

Problem:    t_TI and t_TE are output when using 'visualbell'. (Dominique
            Pelle)
Solution:   Do not change the terminal mode for a short sleep.  Do not output
            t_TI and t_TE when switching to/from TMODE_SLEEP. Make tmode an
            enum.
diff --git a/src/proto/os_vms.pro b/src/proto/os_vms.pro
index c1cfd44..b58118d 100644
--- a/src/proto/os_vms.pro
+++ b/src/proto/os_vms.pro
@@ -1,5 +1,5 @@
 /* os_vms.c */
-void mch_settmode(int tmode);
+void mch_settmode(tmode_T tmode);
 int mch_get_shellsize(void);
 void mch_set_shellsize(void);
 char_u *mch_getenv(char_u *lognam);