Provide an option to run the anticongestion ntpd leapfile fetch in

the background.

Original patch submitted by feld@. I added the "optional" bit.

Submitted by:	feld (original patch)
MFC after:	2 weeks

etc/defaults/periodic.conf

@@ -141,6 +141,8 @@ daily_status_mail_rejects_shorten="NO"			# Shorten output
 
 # 480.leapfile-ntpd
 daily_ntpd_leapfile_enable="YES"			# Fetch NTP leapfile
+daily_ntpd_leapfile_background="NO"			# Fetch NTP leapfile
+							# in the background
 
 # 480.status-ntpd
 daily_status_ntpd_enable="NO"				# Check NTP status

etc/periodic/daily/480.leapfile-ntpd

@@ -13,8 +13,15 @@ fi
 
 case "$daily_ntpd_leapfile_enable" in
     [Yy][Ee][Ss])
-        anticongestion
-        service ntpd onefetch
+	case "$daily_ntpd_leapfile_background" in
+	[Yy][Ee][Ss])
+	    (anticongestion && service ntpd onefetch) &
+	    ;;
+	*)
+	    anticongestion
+	    service ntpd onefetch
+	    ;;
+	esac
         ;;
 esac