Move the dependencies listed in BASE_PKGS from projcts-dir.mk and
topdir.mk into project.conf.
Due to various hen-and-egg problems on a minimal system, in some
situations these packages can't be installed from project.conf. The
same is true with BASE_PKGS, however, so remove it, at least that
does away with some redundancy.
Signed-off-by: Jan Lindemann <jan@janware.com>