add libmagic dependency

Suricata, added in #21463, fails to build with

```
checking for sechash.h... no
checking magic.h usability... no
checking magic.h presence... no
checking for magic.h... no
configure: error: magic.h not found ...
```

[The docs](https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Upgrading_Suricata_11_to_Suricata_12) suggest that libmagic should be required.