avahi: enable mDNSResponder compatibility

[cho-m]

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At least needed for serialosc.

Similar to Arch Linux package where compatibility is enabled and symlink is added https://github.com/archlinux/svntogit-packages/blob/packages/avahi/trunk/PKGBUILD

[BrewTestBot]

🤖 A scheduled task has triggered a merge.