This exposes a /etc/timezone with the current timezone, as per the old
debian spec: https://wiki.debian.org/TimeZoneChanges
In case we're using the session-helper this will be extracted from
the host config and applied whenever that changes.
Normally timezone info is specified by /etc/localtime being a symlink
into the locale data, and you can look at the symlink value itself.
However, in the sandbox we can't update a symlink in /etc at runtime,
nor can we make it of the canonical form as that would point into the
runtime. This is why /etc/timezone is used.
This fixes https://github.com/flatpak/flatpak/issues/2190Closes: #2214
Approved by: alexlarsson
0b6844f39e