image_signing: add log message when signing ARC++

Instead of only logging when ARC++ is not present, also report when we
found an ARC++ image about to be re-signed.

BUG=None
TEST=See info message when running sign_official_build.sh
BRANCH=None

Change-Id: I0d983d38048c4b8dace51e4ea25e23c7cf1da3d7
Reviewed-on: https://chromium-review.googlesource.com/942021
Commit-Ready: Nicolas Norvez <norvez@chromium.org>
Tested-by: Nicolas Norvez <norvez@chromium.org>
Reviewed-by: Victor Hsieh <victorhsieh@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/image_signing/sign_official_build.sh b/scripts/image_signing/sign_official_build.sh
index caf8940..7969179 100755
--- a/scripts/image_signing/sign_official_build.sh
+++ b/scripts/image_signing/sign_official_build.sh
@@ -730,6 +730,7 @@
     return
   fi
 
+  info "Found ARC image version '${arc_version}', re-signing APKs."
   "${SCRIPT_DIR}/sign_android_image.sh" "${rootfs_dir}" "${KEY_DIR}/android"
 
   sudo umount "${rootfs_dir}"