Make submodule update faster with multiprocessing

	git worktree add -f $worktree --detach origin/master

	cd $worktree

	local numcpu=`lscpu -p|grep '^[^#]'|wc -l`

	git submodule sync --recursive

	git submodule update --init --recursive

	git submodule update --init --recursive \

		-j $(((numcpu>1)?(numcpu-1):(numcpu)))

	git submodule foreach '

		setting="submodule.${name}.auto-update";