* date.c: Pacify GCC 4.7.3.

(atof, getlogin, mktime, strchr, time, strftime):
Remove old-style declarations.  GCC 4.7.3 warns about them,
and they aren't needed nowadays anyway.
(main) [HAVE_SETTIMEOFDAY != 2]: "Use" dsttime and minuteswest
to pacify GCC 4.7.3.
* localtime.c: Fix integer overflow bug in mktime implementation.

(tmcomp): Don't mess up when atmp->tm_year - btmp->tm_year overflows.
This can happen when mktime is invoked on a struct tm with tm_year
equal to INT_MIN.
Add FreeBSD-style -r option to 'date'.

* 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.
Move links to 'backward' if they exist only because of country codes.

* backward: Move links here from other files, if the only reason
they existed was to fill out zone.tab.  Zones are now allowed to
cross national borders, so a zone now need not exist merely
because there's a national border.  Sort the list consistently.
None of this changes any time stamp in the database.
* checktab.awk: Don't require that zone.tab's column 3 be unique.
* europe (Europe/Jersey, Europe/Guernsey, Europe/Isle_of_Man)
(Europe/Mariehamn, Europe/Busingen, Europe/Vatican, Europe/San_Marino)
(Arctic/Longyearbyen, Europe/Ljubljana, Europe/Podgorica)
(Europe/Sarajevo, Europe/Skopje, Europe/Zagreb, Europe/Bratislava):
* northamerica (America/St_Barthelemy, America/Marigot):
* southamerica (America/Lower_Princes, America/Kralendijk):
Move links to 'backward'.
* zone.tab: Give more details about how different rows can have
duplicate column 1 or column 3.  For each link moved to 'backward',
change column 3 to be the non-backward name.