am bb026f6f: add bootloader restrictions to OTA metadata

Merge commit 'bb026f6f6725fbdaaf4b1170e5cf5f00a439bfb4' into froyo-plus-aosp

* commit 'bb026f6f6725fbdaaf4b1170e5cf5f00a439bfb4':
  add bootloader restrictions to OTA metadata