When building from tarball git tag is not available.
We need to pass version number manually.
This chnage is cosmetic, but will allow users to easily
identify version and source of their bootloader.
Package secondary LK bootloader for some Qualcomm devices
(for now: msm8916, msm8974, msm8226).
Bootloader binary is built from source in x86_64 chroot.
Two targets are built in a sequence. Then package is split
into 2 subpackages, each of them installs `/boot/lk2nd.img`.
So the end result is - lk2nd-msm8916 and lk2nd-msm8974 can't
be installed at the same time.
Device- packages then can depend on specific subpackage of this
package and have proxy-bootloader image ready to use in /boot.
This can improve user experience with installing postmarketOS on
several devices using only pmbootstrap tool.
At the very least, pmbootstrap can suggest user to flash lk2nd
immediately after `pmbootstrap install` or even offer some kind
of `pmbootstrap flasher` integration.
This will also open possibilities to automatically update and flash
lk2nd using package manager, it we ever want this.
