package/tzdata: fix installation commands

If the destination directory already exists (e.g. because of a re-run or
a custom skeleton), then the zoneinfo files will be installed in a
sub-directory of where we are trying to install them.

Fix that by creating the destination directory and copying the content
of the source directory.

Also fix the host install commands to match what we do in the target
install commands.

Reported-by: Martin Dorwig <dorwig@tetronik.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>