Ensure all files in the ISO's Rock Ridge file system are owned by root

archiso/mkarchiso:
Add the -rational-rock option to xorriso.
This is a preparatory step for creating ISOs as a regular user. See https://gitlab.archlinux.org/archlinux/archiso/-/issues/40 .

archiso/mkarchiso

@@ -309,6 +309,7 @@ command_iso () {
         xorriso -as mkisofs -quiet \
             -iso-level 3 \
             -full-iso9660-filenames \
+            -rational-rock \
             -volid "${iso_label}" \
             -appid "${iso_application}" \
             -publisher "${iso_publisher}" \
@@ -324,6 +325,7 @@ command_iso () {
         xorriso -as mkisofs \
             -iso-level 3 \
             -full-iso9660-filenames \
+            -rational-rock \
             -volid "${iso_label}" \
             -appid "${iso_application}" \
             -publisher "${iso_publisher}" \