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_amiga.pro b/src/proto/os_amiga.pro
index 8e12f4d..b2ad9c3 100644
--- a/src/proto/os_amiga.pro
+++ b/src/proto/os_amiga.pro
@@ -31,7 +31,7 @@
 int mch_nodetype(char_u *name);
 void mch_early_init(void);
 void mch_exit(int r);
-void mch_settmode(int tmode);
+void mch_settmode(tmode_T tmode);
 int mch_get_shellsize(void);
 void mch_set_shellsize(void);
 void mch_new_shellsize(void);