Fix calculations in clone_update_unexp_hooks()

Fix calculations in clone_update_unexp_hooks()

Changes v3:
(1) Fix typo (q --> p).

(1) This commit fixes the calculations when updating paths in lxc.hooks.*
    entries. We now also update conf->unexpandend_alloced which hasn't been
done prior to this commit.

(2) Also we use the stricter check:

    	if (p >= lend)
    		continue;

    This should deal better with invalid config files.

(3) Insert some spaces between operators to increase readability.

(4) Use gotos to simplify function and increase readability.

Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>