tty: ^C while prompted re-displays last message

- attempt to determine if tty_wait_synch() is called during the ending
 dialogs due to an interrupt, and not re-display the previous message
 at the wrong time
- also, "msg_window display anomaly" fix was missing code to still treat ^P
 properly while in a prompt

win/tty/getline.c

@@ -73,7 +73,10 @@ getlin_hook_proc hook;
 		}
 		if(c == '\020') { /* ctrl-P */
 		    if (iflags.prevmsg_window) {
+			int sav = ttyDisplay->inread;
+			ttyDisplay->inread = 0;
 			(void) tty_doprev_message();
+			ttyDisplay->inread = sav;
 			tty_clear_nhwindow(WIN_MESSAGE);
 			cw->maxcol = cw->maxrow;
 			addtopl(query);