net_test: introduce build_all_rootfs.sh
am: de51b09901

Change-Id: I274460e9ce71e3d7be0257b124bad6790a1c114e
tree: 12701e12bdc5eb29f3ccf1bef8a4358d51e9eee4
  1. devicetree/
  2. net/
  3. Android.bp