also find std kernels on ESP/EFI/Gentoo

[Nowa-Ammerlaan]

These kernels are installed by installkernel[efistub] for efi stub booting (not UKI booting, UKIs are in ESP/EFI/Linux)

Closes: #28

[Nowa-Ammerlaan]

Still TODO (in a follow-up PR):

• blsspec.py is responsible for cleaning up UKIs in ESP/EFI/Linux. We only run blsspec.py if we find loader directory on the ESP, this directory belongs to systemd-boot. However, we can also use UKIs without sd-boot, for example with refind or directly from firmware.
• "Traditional" Debian installkernel also installs the usual config and System.map in the UKI directory ESP/EFI/Linux. These are not cleaned up by blsspec.py.

So this PR fixes cleaning up plain kernel images installed for EFI stub booting (ESP/EFI/Gentoo USE=efistub). We still need to improve UKI clean-up so it works without sd-boot (ESP/EFI/Linux USE="-systemd -systemd-boot").

[mgorny]

Also, I'm sorry to say but this would use some test case.

[mgorny]

Thanks! Lemme know if you want me to make a release now, or if you're going to submit more changes first.

[Nowa-Ammerlaan]

Thanks! Lemme know if you want me to make a release now, or if you're going to submit more changes first.

Thanks, there will be a bit more so I think it makes sense to wait before releasing.

• This PR fixed sys-kernel/installkernel[efistub]
• Then there's this one which fixes sys-kernel/installkernel[-systemd,uki] and sys-kernel/installkernel[-systemd-boot,uki]: Fixes for UKI without sd-boot, UKI with legacy installkernel, and rEFInd #51
• And there is this issue for sys-kernel/installkernel[refind] that I'd like to fix: eclean-kernel removes icon file installed by installkernel[refind] #49 Should be a simple matter, the issue occurs because refind requires that the icon file has the same name as the kernel + .png. Therefore we detect the icon file as if it were a kernel, but we can simply add an exception for this.
• And finally I'd like to look into reading os-release instead of hardcoding "Gentoo"/"gentoo" which would mirror the changes in the latest sys-kernel/installkernel.