Update overlay.

bsp/scripts/clean_external_packages.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+build_dir=$1
+external_dir=$2
+
+echo "build dir : $build_dir"
+echo "external dir : $external_dir"
+
+for file in ${external_dir}*
+do
+	base_file=`basename $file`
+	full_file=`compgen -f ${build_dir}/${base_file}-*`
+	#echo "Processing $base_file"
+	#echo "  >> $full_file"
+	if [ -n "$full_file" ]; then
+  		# Do something when var is non-zero length
+		rm ${full_file}/.stamp_built
+	fi
+done