replace it with logic that simply uses "." to load
files directly. for this, "vcfg" is added as a variable
in coreboot target.cfg files, referring to a directory
in config/vendor/ containing a file named pkg.cfg, and
this file then contains the same variables as the
erstwhile config/vendor/sources

config/git files are now directories, also containing
pkg.cfg files each with the same variables as before,
such as repository link and commit hash

this change results in a noticeable reduction in code
complexity within the build system.

unified reading of config files: new function setcfg()
added to lib.sh

setcfg checks if a config exists. if a 2nd argument is
passed, it is used as a return value for eval, otherwise
a string calling err is passed. setcfg output is passed
through eval, to set strings based on config; eval must
be used, so that the variables are set within the same
scope, otherwise they'd be set within setcfg which could
lead to some whacky results.

there's still a bit more more to do, but this single change
results in a substantial reduction in code complexity.

Signed-off-by: Leah Rowe <leah@libreboot.org>

it's ok for now to use it as a backup.

where only github was specified, i mirrored each
given repository to codeberg as main repo for lbmk.

Signed-off-by: Leah Rowe <leah@libreboot.org>

With this change, it's still possible to have a single
file at config/git/revisions, but this has been scrapped.

Instead, multiple files now exist under config/git/ with
the same modules declared, but the files are separated
logically. List of files under config/git:

* bios_extract
* biosutilities
* coreboot
* flashrom
* grub (gnulib also defined here)
* me_cleaner
* memtest86plus
* seabios
* serprog (multiple projects defined)
* u-boot
* uefitool

The rationale behind this change is simple: in the future,
we will stop relying on build systems within imported
projects for the import of git submodules. Instead, we
will handle them directly in lbmk.

Additionally, a Linux payload is planned for Libreboot, made
easier by the recent audit (script handle/make/config makes
it easy to integrate Linux, and handle cross-compilers for
userland utilities); a "linux" file under config/git/ could
also define rules for each project besides linux, such as
musl libc, busybox and other utilities.

Signed-off-by: Leah Rowe <leah@libreboot.org>