Destroy options if ares_save_options fails

It's possible that, if ares_save_options failed, the opts structure
would contain some allocated memory. Calling ares_destroy_options in
this case is safe, because ares_save_options zeroes out the memory
initially.

ares_init.c

@@ -266,7 +266,10 @@ int ares_dup(ares_channel *dest, ares_channel src)
      which is most of them */
   rc = ares_save_options(src, &opts, &optmask);
   if(rc)
+  {
+    ares_destroy_options(&opts);
     return rc;
+  }
 
   /* Then create the new channel with those options */
   rc = ares_init_options(dest, &opts, optmask);