Add gptboot_enable rc variable, which allows to turn gptboot reporting off in

case user wants to implement his own actions and doesn't want the attributes to
vanish.

Obtained from:	Wheel Systems Sp. z o.o. http://www.wheelsystems.com
MFC after:	3 days

etc/defaults/rc.conf

@@ -58,6 +58,8 @@ rc_conf_files="/etc/rc.conf /etc/rc.conf.local"
 # ZFS support
 zfs_enable="NO"		# Set to YES to automatically mount ZFS file systems
 
+gptboot_enable="YES"	# GPT boot success/failure reporting.
+
 # Experimental - test before enabling
 gbde_autoattach_all="NO" # YES automatically mounts gbde devices from fstab
 gbde_devices="NO" 	# Devices to automatically attach (list, or AUTO)

etc/rc.d/gptboot

@@ -34,6 +34,7 @@
 . /etc/rc.subr
 
 name="gptboot"
+rcvar=`set_rcvar`
 start_cmd="gptboot_report"
 
 gptboot_report()

share/man/man5/rc.conf.5

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 13, 2010
+.Dd November 24, 2010
 .Dt RC.CONF 5
 .Os
 .Sh NAME
@@ -1575,6 +1575,17 @@ If set to
 .Pa /etc/rc.d/zfs
 will attempt to automatically mount ZFS file systems and initialize ZFS volumes
 (ZVOLs).
+.It Va gptboot_enable
+.Pq Vt bool
+If set to
+.Dq Li YES ,
+.Pa /etc/rc.d/gptboot
+will log if the system successfully (or not) booted from a GPT partition,
+which had the
+.Ar bootonce
+attribute set using
+.Xr gpart 8
+utility.
 .It Va gbde_autoattach_all
 .Pq Vt bool
 If set to