hammer: add support for building Kea on latest Alpine, Ubuntu, Fedora and FreeBSD

Alpine 3.13 was released on 14 January 2021, https://alpinelinux.org/posts/Alpine-3.13.0-released.html
Fedora 34
Ubuntu 21.04
FreeBSD 13

Support to hammer can now be added.

Edited Jun 07, 2021 by Michal Nowikowski

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