really fix install_t in containers

[cgwalters]

I'm not sure if something changed here, or my code never actually worked but basically we currently fail to bootc install with unknown types.

[akdev1l]

I hit this bug while trying to create a bootc image based on Arch Linux

It seems that it can be worked around by disabling SELinux

[akdev1l]

so we tried this on a fedora host with SELinux disabled and --disable-selinux flag.

This allowed us to skip the install_t issue when creating an bootc image from arch linux (they don't ship selinux policies so everything is unlabeled). However we ran into some problems.

We realized matchpathcon and chcon are both used even when selinux is disabled at the kernel level and --disable-selinux has been passed so the target installed system should not necessarily have labels (though I guess it is nice to have them in case the user wants to turn selinux on later, it seems the idea behind --disable-selinux is to support non-selinux enabled system)

We were able to patch this by simply overwriting the binaries, matchpathcon was hardcoded to output a specific selinux context and chcon was overwritten to be equal to /bin/true so both commands would succeed unconditionally. (we're trying not to touch bootc itself for now, just trying to make it work on a non-fedora system as proof of concept)

is this behaviour expected?

[cgwalters]

Thanks for the report; any chance you could test out #96 ?

[cgwalters]

This should be fixed by #284