* Avoids the need to download the IANA database.
* Heavily based on contributions by Aaron Bishop.
* Turn on with -DUSE_OS_TZDB, off by default.
* Not supported on Windows.
* Disables HAS_REMOTE_API.
* get_tzdb().version only supported on Apple. This string has
the value "unknown" elsewhere.
* Leap second support is missing on Apple, and may not be on your
platform either (please report). Leap second support is enabled,
disabled with -DMISSING_LEAP_SECONDS.
Without leap second support, utc_time, tai_time, and gps_time (and
those clocks) are not available.
* On Apple, time zone transitions are only supported in the range:
1901-12-13 20:45:52 to 2038-01-19 03:14:07
* On Linux, time zone transitions are only as far in the future as
the OS-provided transitions go. There is no support for POSIX-
style transitions.
Make validate work for C++11 because the library supports it.
Fix an unused variable mistake i made earlier.
Make constructor public, seems it should be. Possible compiler bug?