.gitcheck: re-write entirely. force global config.

the way the old script worked was extremely hacky

it's cleaner just to make the user configure git

i haven't used anything from the old .gitcheck script,
which is now deleted. i completely re-wrote this, in
a much simpler way.

this is less maintenance now, when things change in
the upstream projects. coreboot makes heavy use of git
within its build system

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

fetch_trees

@@ -39,6 +39,7 @@ main()
 	if [ "$(id -u)" = "0" ]; then
 		err "running lbmk as root as not permitted"
 	fi
+	./checkgit || err "Please read: https://libreboot.org/docs/build/"
 
 	rm -f "${cfgsdir}"/*/seen || err_rm_seen "main 1"