If the container does not already contain an /etc/localtime
timezone definition, then copy a definition from the host to
the container.  This is often a symlink to an appropriate
system timezone definition files and is presumed to exist in
Signed-off-by: Michael H. Warfield <mhw@WittsEnd.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>