shutils/cgroups: Use busybox `ps` to fix output format

Different `ps` implementations (e.g. Android vs GNU) have different
default columns and process selections.
diff --git a/devlib/bin/scripts/shutils.in b/devlib/bin/scripts/shutils.in
index 0bfab5c..2442386 100755
--- a/devlib/bin/scripts/shutils.in
+++ b/devlib/bin/scripts/shutils.in
@@ -9,6 +9,7 @@
 SED=${SED:-$BUSYBOX sed}
 CAT=${CAT:-$BUSYBOX cat}
 AWK=${AWK:-$BUSYBOX awk}
+PS=${PS:-$BUSYBOX ps}
 
 ################################################################################
 # CPUFrequency Utility Functions
@@ -156,7 +157,7 @@
 
 	[ "x$FILTERS" = "x" ] && exit 0
 
-	PIDS=`ps | $GREP $FILTERS | $AWK '{print $2}'`
+	PIDS=`$PS -o comm,pid | $GREP $FILTERS | $AWK '{print $2}'`
 	PIDS=`echo $PIDS`
 	echo "PIDs to save: [$PIDS]"
 	for TID in $PIDS; do