localtime
=========

POSIX specification:
 https://pubs.opengroup.org/onlinepubs/9699919799/functions/localtime.html

Gnulib module: localtime

Portability problems fixed by Gnulib:

  * On native Windows platforms (mingw, MSVC), this function works incorrectly when the environment variable TZ has been set by Cygwin.

Portability problems not fixed by Gnulib:

  * On some platforms, this function loops forever for values near extrema (such as the year -2**31): Mac OS X 10.6. You can use the time_rz module to work around the problem.

  * On some platforms, this function returns nonsense values for unsupported arguments (like 2^56), rather than failing: FreeBSD 10.

  * Native Windows platforms (mingw, MSVC) support only a subset of time zones supported by GNU or specified by POSIX.  See tzset.