Restoring a game can return to the wishing prompt

In TTY or curses, if the terminal goes away while you're in the wishing
prompt, return to the prompt when the game is restored.

Breaks saves.

include/flag.h

@@ -246,6 +246,7 @@ struct instance_flags {
     boolean invis_goldsym; /* gold symbol is ' '? */
     boolean in_lua;        /* executing a lua script */
     boolean lua_testing;   /* doing lua tests */
+    boolean term_gone;     /* terminal is gone, abort abort abort */
     boolean nofollowers;   /* level change ignores pets (for tutorial) */
     boolean partly_eaten_hack; /* extra flag for xname() used when it's called
                                 * indirectly so we can't use xname_flags() */