Missing directory structure added.

.gitkeep files are used to add empty directories to repository.
	new file:   ../build/.gitkeep
	new file:   rootfs.base_exclude/src/.gitkeep
	new file:   rootfs.base_exclude/tmp/.gitkeep
	new file:   rootfs.base_exclude/usr/share/doc/.gitkeep
	new file:   rootfs.base_exclude/usr/share/man/.gitkeep
	new file:   rootfs.base_exclude/usr/src/.gitkeep
	new file:   rootfs.base_exclude/var/cache/apt/.gitkeep