what's the use? `validate` should be set to `False` (hard), and there are no incoming `build_options` in the `ec_filename_for` function?

Maybe there will need to be at some point (because this approach obviously only works for easyconfig format v1.0 files), but not right now... The `ec_filename_for` is only used by the `tweak` function, which is linked to the `--try-X` command line options. Stuff for later, imho.