Recent code to try and detect if a terminal supports UTF-8 by printing to it

fails spectacularly on (at least) sparc64, so disable it for now. Thanks to
naddy and Josh Elsasser for help and testing.

tmux.1

@@ -109,13 +109,11 @@ flag is ignored.
 Unlock the server.
 .It Fl u
 .Nm
-attempts to guess if the terminal is likely to support UTF-8 by first checking
+attempts to guess if the terminal is likely to support UTF-8 by checking
 the
 .Ev LANG
-environment variable for the string "UTF-8", and then by - if the terminal
-looks suitable - trying to print a UTF-8 character and measuring the cursor
-movement.
-These are not always successful: the
+environment variable for the string "UTF-8". 
+This is not always correct: the
 .Fl u
 flag explicitly informs
 .Nm

tty.c

@@ -134,7 +134,9 @@ tty_start_tty(struct tty *tty)
 	struct termios	 tio;
 	int		 what;
 
+#if 0
 	tty_detect_utf8(tty);
+#endif
 
 	if (tcgetattr(tty->fd, &tty->tio) != 0)
 		fatal("tcgetattr failed");
@@ -204,6 +206,7 @@ tty_stop_tty(struct tty *tty)
 		tty_raw(tty, "\033[?1000l");
 }
 
+#if 0
 void
 tty_detect_utf8(struct tty *tty)
 {
@@ -278,6 +281,7 @@ tty_detect_utf8(struct tty *tty)
 	if (tcsetattr(tty->fd, TCSANOW, &old_tio) != 0)
 		fatal("tcsetattr failed");
 }
+#endif
 
 void
 tty_fill_acs(struct tty *tty)