In several places the code and documentation incorrectly used
"UTC" to describe time stamps that might precede the introduction
of UTC and for which UTC is therefore undefined. Change these
uses to "UT", as that's the correct term when talking about these
time stamps. Problem reported by Steve Allen in
<http://mm.icann.org/pipermail/tz/2013-September/019907.html>.
The major compatibility issue here is with 'zdump -v'; it'll now
output "UT" instead of the possibly-incorrect "UTC".
Many files change in minor ways in the commentary.
* zdump.c (show):
* zic.c (inzsub, addtype):
In output, say "UT" rather than "UTC", since the time stamp we're
talking about might precede the introduction of UTC.
* date.1: Document -r.
* date.c (main, usage): Support -r.
(main, reset): Remove EBUG code.
(display): New argument NOW. Do not exit; that's now the
caller's responsibility. All callers changed.
(display, timeout, convert, checkfinal, iffy):
Don't assume that localtime and gmtime succeed.
This prevents a core dump for, e.g., 'date -r 0xffffffffffffffff'.
* private.h: Include float.h.
(strtoimax): New macro, for pre-C99 systems that lack strtoimax.
(time_t_min, time_t_max): New constants, from zdump, with
different names to avoid a clash when zdump.c includes private.h.
