Complete the migration towards utmpx.

- Add a notice to UPDATING, explaining users may need to recompile
  applications that use the old database.
- Bump __FreeBSD_version.

UPDATING

@@ -22,6 +22,23 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 9.x IS SLOW:
 	machines to maximize performance.  (To disable malloc debugging, run
 	ln -s aj /etc/malloc.conf.)
 
+20100113:
+	The utmp user accounting database has been replaced with utmpx,
+	the user accounting interface standardized by POSIX.
+	Unfortunately the semantics of utmp and utmpx don't match,
+	making it practically impossible to support both interfaces.
+	The user accounting database is used by tools like finger(1),
+	last(1), talk(1), w(1) and ac(8).
+
+	All applications in the base system use utmpx.  This means only
+	local binaries (e.g. from the ports tree) may still use these
+	utmp database files.  These applications must be rebuilt to make
+	use of utmpx.
+
+	After the system has been upgraded, it is safe to remove the old
+	log files (/var/run/utmp, /var/log/lastlog and /var/log/wtmp*),
+	assuming their contents is of no importance anymore.
+
 20100108:
 	Introduce the kernel thread "deadlock resolver" (which can be enabled
 	via the DEADLKRES option, see NOTES for more details) and the

sys/sys/param.h

@@ -58,7 +58,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 900006	/* Master, propagated to newvers */
+#define __FreeBSD_version 900007	/* Master, propagated to newvers */
 
 #ifndef LOCORE
 #include <sys/types.h>