Currently when building installation packages for uncommon languages the
make/dmake process may break at the end (after several minutes) because some
files like readmes or license text are missing for that locale. To work around
this files need to be copied manually from one existing locale to the missing
locale. The problem however is that the build only breaks at the end which is
very annoying if you need to build a multi installation set and get this
probelem several times each after some minutes of building passed only.

In order to save time the make process should complain right at the start about
missing files that need to be copied manually anyway when they are not provided
by the build process.