package: add base dependency to every package

Move "dependencies" "dirs" "prepare" dependencies from "toolchain" to
every package.
This way we can build correctly every package right after the clean
stage.
As example with this commit we can build successfully the glibc right
after the clean stage:
	make clean glibc

This is also a step forward supporting top-level parallel make.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>