Update to pacify recent GCC's static checking.

These changes pacify gcc 4.8.2-19ubuntu1 on Ubuntu 14.04,
and take advantage of recently-added GCC options when compiling
with GCC_DEBUG_FLAGS.
* Makefile (GCC_DEBUG_FLAGS): Add -Wdeclaration-after-statement,
-Wjump-misses-init, -Wsuggest-attribute=format.
* date.c (copyright, sccsid):
* strftime.c (sccsid):
Remove unused vars.
* date.c (main):
* localtime.c (tzparse):
Remove no-longer-needed uses of INITIALIZE; GCC is smart enough to
figure these out on its own now.
* localtime.c (gmtsub): Redo initialization of gmt_is_set to pacify GCC.
Retry malloc next time even if it failed this time.
* private.h, zdump.c (GNUC_or_lint): Remove, as it provoked a GCC
diagnostic about unused macros in some cases.  Instead, just use
'lint'.  All uses removed.
(TZ_DOMAIN): Don't define unless needed, as otherwise it provokes
a GCC diagnostic about unused macros.
* private.h (INITIALIZE): Simplify accordingly.
* NEWS: Document this.