Add tty_flush() to rl_forced_update_display()

Forcing update should flush, otherwise weird stuff happen when writing
to console asynchronously (cursor is moved, text is not displayed).

Signed-off-by: Jakub Pawlowski <jakubpawlo@gmail.com>
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/editline.c

@@ -1170,6 +1170,7 @@ void rl_clear_message(void)
 void rl_forced_update_display()
 {
     redisplay();
+    tty_flush();
 }
 
 char *readline(const char *prompt)