Respect TZDIR environment variable #1265
Description
The TZDIR variable can be set to override the path to the time zone database, at least in glibc. See ogham/exa#856.
We should also merge the two places where we define the search dirs.
Local/unix.rs:
#[cfg(target_os = "aix")]
const TZDB_LOCATION: &str = "/usr/share/lib/zoneinfo";
#[cfg(not(any(target_os = "android", target_os = "aix")))]
const TZDB_LOCATION: &str = "/usr/share/zoneinfo";And local/tz_info/timezone.rs:
#[cfg(unix)]
const ZONE_INFO_DIRECTORIES: [&str; 4] =
["/usr/share/zoneinfo", "/share/zoneinfo", "/etc/zoneinfo", "/usr/share/lib/zoneinfo"];