[Bug libstdc++/108409] std::chrono::current_zone() doesn't work on AIX

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108409

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-01-14

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
describes the format of the TZ variable when it's not an IANA name.

When TZ does not name an IANA zone, we could potentially create a new
chrono::time_zone object, generated from the std and dst names, with the
appropriate offsets and DST transitions. Then current_zone() would return a
pointer to that custom zone.