Upstream report, without better patch yet:
http://bugs.gw.com/view.php?id=366

--- tc.who.c.orig	2014-06-26 11:21:43 +0200
+++ tc.who.c	2014-06-26 11:21:58 +0200
@@ -60,6 +60,8 @@
 #  define TCSH_PATH_UTMP _PATH_UTMPX
 # elif defined(UTMPX_FILE)
 #  define TCSH_PATH_UTMP UTMPX_FILE
+# elif defined(UTMP_FILE)
+#  define TCSH_PATH_UTMP UTMP_FILE
 # elif __FreeBSD_version >= 900000
 #  /* Why isn't this defined somewhere? */
 #  define TCSH_PATH_UTMP "/var/run/utx.active"