add build image

board/miyoo/main/apps/fbgrab/screenshot.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+name=/mnt/screenshots/system
+mkdir -p /mnt/screenshots
+if [[ -e $name.png ]] ; then
+    i=1
+    while [[ -e $name-$i.png ]] ; do
+        let i++
+    done
+    name=$name-$i
+fi
+/mnt/apps/fbgrab/fbgrab "$name".png