rc.suspend: execute rc-scripts with suspend keyword

For symmetry with rc.resume, give rc.suspend the ability to execute
rc-scripts. Use the suspend keyword for that.

Use-case is for setting a wake-up time, e.g. via efiwake.

Reviewed by:	christos
Approved by:	markj (mentor)
Differential Revision:	https://reviews.freebsd.org/D39965

libexec/rc/rc.suspend

@@ -43,15 +43,28 @@ fi
 
 echo $$ 2> /dev/null > /var/run/rc.suspend.pid
 
-# If you have troubles on suspending with PC-CARD modem, try this.
-# See also contrib/pccardq.c (Only for PAO users).
-# pccardq | awk -F '~' '$5 == "filled" && $4 ~ /uart/ \
-#	{ printf("pccardc power %d 0", $1); }' | sh
-
 # If a device driver has problems suspending, try unloading it before
 # suspend and reloading it on resume.  Example:
 # kldunload usb
 
+. /etc/rc.subr
+
+load_rc_config
+
+rcorder_opts="-k suspend"
+
+case ${local_startup} in
+[Nn][Oo] | '') ;;
+*)     find_local_scripts_new ;;
+esac
+
+files=`rcorder ${rcorder_opts} /etc/rc.d/* ${local_rc} 2>/dev/null`
+
+for _rc_elem in $files; do
+	debug "run_rc_script $_rc_elem suspend"
+	run_rc_script $_rc_elem suspend
+done
+
 /usr/bin/logger -t $subsystem suspend at `/bin/date +'%Y%m%d %H:%M:%S'`
 /bin/sync && /bin/sync && /bin/sync
 /bin/sleep 3