fix issue with idle-check.sh cronjob not sourcing in global env

variables correctly because cron only uses a minimal set of env
variables. Now idle-check.sh sources in /etc/profile for receiving the
global variables correctly.

buildroot-external/rootfs-overlay/bin/idle-check.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# shellcheck shell=dash disable=SC2169,SC3010
+# shellcheck shell=dash disable=SC2169,SC3010 source=/dev/null
 #
 # System Idle Shutdown (idle-check.sh)
 # ------------------------------------
@@ -50,6 +50,9 @@
 # published by the Free Software Foundation, version 2.
 #
 
+# source global env variables
+. /etc/profile
+
 # default config
 [[ -z "${SHUTDOWN_IDLE_INTERVAL}" ]] && SHUTDOWN_IDLE_INTERVAL=5
 [[ -z "${SHUTDOWN_IDLE_TIME}" ]] && SHUTDOWN_IDLE_TIME=86400