Use @basename@ in enumeration type templates

Use @basename@ in enumeration type templates

The @filename@ directive will use the full path of the file being parsed
for enumeration types; we should use @basename@, instead, as it improves
the reproducibility of the build by using only the file name.

Backport of 4040f76529bbf6d3310a71df2d37c9d95af83892 from main.