Request: slirp_version_string() should append a suffix for non-tagged versions

I'd expect slirp_version_string() to append a suffix for non-tagged versions (i.e. on git master).

e.g. slirp_version_string()= "4.2.0+dev".

Can be a new function like void slirp_version(SlirpVersion *out) if such change is considered to be breaking. It would be even better if void slirp_version(SlirpVersion *out) can also return the git commit hash.