In Makefile, SUBS variable is assigned, not appended

This issue is created as a reminder, so that the issue does not need to be discovered again. No immediate action is required.

See line: https://gitlab.esss.lu.se/e3/recipes/drvasyniseghalservice-recipe/-/blob/c44438c337e97bfd743cd5b6af2e79a50b6a2dcd/src/Makefile#L27

Because SUBS variable is set instead of being appended, the highlighted line does not do anything. This looks like an unintended behavior.

On the other hand, the actual cc24.substutions file themselves seem to be specific to one crate only. This makes the content of this substutions file inappropriate for use in a re-usable module. Therefore, it seems also correct to remove this line entirely.