Revert "utils: reimplement/fix mkdir_p()"

This reverts commit 8de4140644f01180f2fdab55b0ab0f13d1c761c6.

This commit was preventing container startup on my machine, making them
all fail with various "No such file or directory" errors.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Revert "start: Detect early failure of the new child"

This reverts commit 5a5c35c3a01afec515e688c8366e6f893985518d.

This commit was preventing startup of containers using lxc hooks and
shutdown of all other containers, requiring the use of a good old
kill -9 to get rid of lxc-start after a container shutdown.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>