elements/dib-init-system: fail to detect init system in some gentoo guest configurations

[Raimonds Cicans]

diskimage-builder: 2.20.3
Host OS: Gentoo (amd64)
Guest OS: Gentoo (amd64)

Problem: guest building fails early if variable GENTOO_PROFILE is set and it does _NOT_ contain word "systemd"

Cause: bug in elements/dib-init-system/dib-init-system

Description:
elements/dib-init-system/dib-init-system miss "else" for following statement:
if [[ "${GENTOO_PROFILE}" =~ systemd ]]; then
    echo "systemd"
fi

Fix: add "else" statement:
if [[ "${GENTOO_PROFILE}" =~ systemd ]]; then
    echo "systemd"
else
    echo "openrc"
fi

Hmmm... IMHO it would be nice to have some environment variable to override auto-detection...

[Raimonds Cicans (raycic)]

Sorry, I'm wrong.

Hmmm... It looks there are several bugs mixed.

Guest VM build fails early if "--no-tmpfs" CLI parameter used or GENTOO_PROFILE contains "hardened" (which automatically turns on "--no-tmpfs").

[Raimonds Cicans (raycic)]

Fails was caused by #1822670

Code mentioned in comments above is little bit more buggy.
Patch attached.

I do not know how this bug affect Gentoo guest building - I still have other errors which do not allow to finish Gentoo guest building.