New review comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/32558#discussion_r691304177

Comment:
This means adding `AC_CHECK_FUNCS(mallinfo)` in `configure.ac` and replacing the test by `#ifdef HAVE_MALLINFO` or something like that?

I think the few cases where they check `HAVE_MALLOC_H` is just to use`mallinfo()`.

Is it worth doing that for us, or proposing it to upstream? It seems a chore having to deal with autoconf since the patch above works ok for us.