tzfile.h is an internal header that should never have been installed.

What's worse, the tzfile.h that gets installed is over 20 years old
and doesn't match the real tzfile.h in libc/time.  This makes the
tree safe for /usr/include/tzfile.h removal.  The TM_YEAR_BASE
define has been moved to time.h temporarily until its usage is
replaced by 1900 in the tree.  Actual removal of tzfile.h is pending
a ports build.  Based on a diff from deraadt@

src/include/time.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: time.h,v 1.25 2013/06/17 19:11:54 guenther Exp $	*/
+/*	$OpenBSD: time.h,v 1.26 2015/03/15 00:41:27 millert Exp $	*/
 /*	$NetBSD: time.h,v 1.9 1994/10/26 00:56:35 cgd Exp $	*/
 
 /*
@@ -166,6 +166,11 @@ int clock_getcpuclockid(pid_t, clockid_t *);
 #endif
 
 #if __BSD_VISIBLE
+
+#ifndef TM_YEAR_BASE
+#define TM_YEAR_BASE	1900
+#endif
+
 char *timezone(int, int);
 void tzsetwall(void);
 time_t timelocal(struct tm *);

src/lib/libutil/check_expire.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: check_expire.c,v 1.10 2014/08/25 07:50:25 doug Exp $	*/
+/*	$OpenBSD: check_expire.c,v 1.11 2015/03/15 00:41:27 millert Exp $	*/
 
 /*
  * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
@@ -45,7 +45,6 @@
 #include <string.h>
 #include <syslog.h>
 #include <time.h>
-#include <tzfile.h>
 #include <login_cap.h>
 #include <bsd_auth.h>
 
@@ -53,6 +52,9 @@
 
 static char *pwd_update(const struct passwd *, const struct passwd *);
 
+#define SECSPERDAY	(24 * 60 * 60)
+#define TWOWEEKS	(2 * 7 * SECSPERDAY)
+
 int
 login_check_expire(FILE *back, struct passwd *pwd, char *class, int lastchance)
 {
@@ -85,8 +87,7 @@ login_check_expire(FILE *back, struct passwd *pwd, char *class, int lastchance)
 		} else {
 			dead = login_getcaptime(lc, "password-dead", 0, 0);
 			warn = login_getcaptime(lc, "password-warn",
-			    2 * DAYSPERWEEK * SECSPERDAY,
-			    2 * DAYSPERWEEK * SECSPERDAY);
+			    TWOWEEKS, TWOWEEKS);
 			if (dead < 0) {
 				syslog(LOG_ERR, "class %s password-dead is %qd",
 					lc->lc_class, dead);