Update timezone code from tzcode 2015g.

This patch updates the timezone code from tzcode 2015g.  The Makefile
and README changes are based on those in Paul's patch
<https://sourceware.org/ml/libc-alpha/2015-05/msg00553.html>.

Tested for x86_64 and x86.

2016-01-06  Paul Eggert  <eggert@cs.ucla.edu>
	    Joseph Myers  <joseph@codesourcery.com>

	* timezone/private.h: Update from tzcode 2015g.
	* timezone/tzfile.h: Likewise.
	* timezone/tzselect.ksh: Likewise.
	* timezone/zdump.c: Likewise.
	* timezone/zic.c: Likewise.
	* timezone/ialloc.c: Remove file.
	* timezone/scheck.c: Likewise.
	* timezone/Makefile (extra-objs): Remove variable.
	($(objpfx)zic): Do not depend on scheck.o and ialloc.o.
	(tz-cflags): Add -DHAVE_GETTEXT -DUSE_LTZ=0
	-Wno-maybe-uninitialized.
	(CFLAGS-zdump.c): Remove -fwrapv -DNOID -DHAVE_GETTEXT.
	(CFLAGS-zic.c): Remove -DNOID -DHAVE_GETTEXT.
	(CFLAGS-ialloc.c): Remove variable.
	(CFLAGS-scheck.c): Likewise.
	* timezone/README: Update list of files from tzcode.