Fix a memory-leak in fuzz_vrs.c

src/test/fuzz/fuzz_vrs.c

@@ -38,6 +38,8 @@ fuzz_init(void)
 int
 fuzz_cleanup(void)
 {
+  SMARTLIST_FOREACH(dummy_vote->known_flags, char *, cp, tor_free(cp));
+  smartlist_free(dummy_vote->known_flags);
   tor_free(dummy_vote);
   return 0;
 }