About utmpentry.c:

the utmpx structure defines the ut_tv member a little differently on 
64bit hosts so that a 32bit and 64bit structure can be shared.  So the 
ut_tv is a custom 32bit structure rather than the native 64bit timeval 
structure.  Work around is to assign the submembers instead.

http://bugs.gentoo.org/show_bug.cgi?id=102667

--- a/dm/utmpentry.c
+++ b/dm/utmpentry.c
@@ -291,7 +291,8 @@
 	e->line[sizeof(e->line) - 1] = '\0';
 	(void)strncpy(e->host, up->ut_host, sizeof(up->ut_host));
 	e->name[sizeof(e->host) - 1] = '\0';
-	e->tv = up->ut_tv;
+	e->tv.tv_sec = up->ut_tv.tv_sec;
+	e->tv.tv_usec = up->ut_tv.tv_usec;
 	adjust_size(e);
 }
 #endif