[binarycaching] Provide an option to use an alternative to zip on *NIX systems

[davidchisnall]

Is your feature request related to a problem? Please describe.

zip is not part of POSIX and so is not included in the base install of most *NIX systems. pax is mandated by POSIX and tar is typically installed as a non-standard extension. There's a message interleaved with other output while building that zip isn't installed and so caches can't be used.

Proposed solution

Provide a mechanism for platforms to specify their preferred archive / restore tool. For example, on FreeBSD the preferred tool would likely be tar --lz4 (in the base system, significantly faster than zip).

Note that GitHub can generate tarballs via the same API that it generates zip files and so there is no requirement for even unzip for ports that come from GitHub. For ports from other sources, it is common to provide tarballs rather than zip files for the sources for building on *NIX.

Describe alternatives you've considered

I can install zip, but it is not a great user experience to discover that the lack of a non-standard package has made things slower.

[JackBoosY]

I think we can accept this.