replace fuzzer state magic numbers

include/flag.h

@@ -224,6 +224,12 @@ struct accessibility_data {
             a11y.mon_notices_blocked = 0;                           \
         } } while(0)
 
+enum debug_fuzzer_states {
+    fuzzer_off,
+    fuzzer_impossible_panic,
+    fuzzer_impossible_continue
+};
+
 /*
  * Stuff that really isn't option or platform related and does not
  * get saved and restored.  They are set and cleared during the game