sign_android: don't use xattrs from unsquashfs

We've moved to applying a file based set of selinux policies instead of
taking the ones that were snagged from the image. Remove the policy
attributes and let unsquash do whatever it would do by default.

See https://chat.google.com/room/AAAA45hbdCQ/jkXYe7jMEDk.

BUG=chromium:1141907
TEST=unittests

Change-Id: I0a976fb216e0a07c00c4bb2fb68df6fa1ea00d79
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2511121
Reviewed-by: Yury Khmel <khmel@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Yury Khmel <khmel@google.com>
Commit-Queue: George Engelbrecht <engeg@google.com>
Commit-Queue: Yury Khmel <khmel@google.com>
Tested-by: George Engelbrecht <engeg@google.com>
Auto-Submit: George Engelbrecht <engeg@google.com>
diff --git a/scripts/image_signing/sign_android_image.sh b/scripts/image_signing/sign_android_image.sh
index 28534fc..bd10789 100755
--- a/scripts/image_signing/sign_android_image.sh
+++ b/scripts/image_signing/sign_android_image.sh
@@ -231,7 +231,7 @@
 # Snapshot file properties in a directory recursively.
 snapshot_file_properties() {
   local dir=$1
-  sudo find "${dir}" -exec stat -c '%n:%u:%g:%a:%C' {} + | sort
+  sudo find "${dir}" -exec stat -c '%n:%u:%g:%a' {} + | sort
 }
 
 main() {
@@ -289,7 +289,7 @@
   local system_mnt="${working_dir}/mnt"
 
   info "Unpacking squashfs system image to ${system_mnt}"
-  sudo "${unsquashfs}" -x -f -no-progress -d "${system_mnt}" "${system_img}"
+  sudo "${unsquashfs}" -no-xattrs -f -no-progress -d "${system_mnt}" "${system_img}"
 
   snapshot_file_properties "${system_mnt}" > "${working_dir}/properties.orig"