Port to x32 by fixing type incompatibility with POSIX.

Reported by Elliott Hughes in
<http://mm.icann.org/pipermail/tz/2013-September/020376.html>.
* localtime.c (timezone) [USG_COMPAT]:
(altzone) [ALTZONE]: Now long, not time_t.
* strftime.c (_fmt): Use long, not int, to store timezone.
* NEWS: Document this.

NEWS

@@ -13,6 +13,16 @@ Unreleased, experimental changes
 
     Palestine will fall back at 00:00, not 01:00.  (Thanks to Steffen Thorsen.)
 
+  Changes affecting API
+
+    The types of the global variables 'timezone' and 'altzone' (if present)
+    have been changed back to 'long'.  This is required for 'timezone'
+    by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
+    These variables were originally 'long' in the tz code, but were
+    mistakenly changed to 'time_t' in 1987; nobody reported the
+    incompatibility until now.  The difference matters on x32, where
+    'long' is 32 bits and 'time_t' is 64.  (Thanks to Elliott Hughes.)
+
   Changes affecting the build procedure
 
     Avoid long strings in leapseconds.awk to work around a mawk bug.

localtime.c

@@ -215,12 +215,12 @@ char *			tzname[2] = {
 static struct tm	tm;
 
 #ifdef USG_COMPAT
-time_t			timezone = 0;
+long			timezone = 0;
 int			daylight = 0;
 #endif /* defined USG_COMPAT */
 
 #ifdef ALTZONE
-time_t			altzone = 0;
+long			altzone = 0;
 #endif /* defined ALTZONE */
 
 static int_fast32_t

strftime.c

@@ -492,7 +492,7 @@ label:
 				continue;
 			case 'z':
 				{
-				int		diff;
+				long		diff;
 				char const *	sign;
 
 				if (t->tm_isdst < 0)