Remove Android-related code from halium-boot

[peat-psuwit]

This, combined with a change in lxc-android-config [1], moves the
Android-related code to rootfs, which allows more flexibility in
implementation and ease of update.

Note that one can't merge this branch if this is used for xenial, because the lxc-android-config code doesn't exist there.

[1] https://gitlab.com/ubports/core/hybris-support/lxc-android-config/-/merge_requests/51

[Herrie82]

@Tofee Any comments or suggestions? Seeing UBPorts will be doing their Android mounts via systemd service files, I guess we could do the same at our end and unify our code again?

https://gitlab.com/ubports/core/hybris-support/lxc-android-config/-/merge_requests/51

[Tofee]

@Herrie82 Very interesting idea. We probably lose the "android" boot mode, but it's not useful for us. I wonder if there are consequences on some kernel drivers ? Also, does it still support all the booting modes (rootfs as folder in userdata, or as image, vendor image, etc) ?
This would be nice to try for us too, and would make the boot script more similar to a full-mainlined device initrd script.

[peat-psuwit]

We probably lose the "android" boot mode, but it's not useful for us.

I implemented the "android" mode (which is essentially the charger mode) by changing systemd's default target to a special target which run the container and (mostly) nothing else. In effect, Android code takes over displaying the charger animation from within the container.

Also, does it still support all the booting modes

The rootfs finding code is not removed, so it should still support the same set of "boot modes".