Fuzz testing debug tool

Add code to run a fuzz tester, simulating (more-or-less) random
keyboard mashing. There's no option to turn it on, you need to
set iflags.debug_fuzzer on via a debugger or something along
those lines.

win/tty/wintty.c

@@ -3344,6 +3344,9 @@ tty_nhgetch()
      */
     if (WIN_MESSAGE != WIN_ERR && wins[WIN_MESSAGE])
         wins[WIN_MESSAGE]->flags &= ~WIN_STOP;
+    if (iflags.debug_fuzzer) {
+	i = randomkey();
+    } else {
 #ifdef UNIX
     i = (++nesting == 1) ? tgetch()
                          : (read(fileno(stdin), (genericptr_t) &nestbuf, 1)
@@ -3352,6 +3355,7 @@ tty_nhgetch()
 #else
     i = tgetch();
 #endif
+    }
     if (!i)
         i = '\033'; /* map NUL to ESC since nethack doesn't expect NUL */
     else if (i == EOF)