Put back %changlog section in RPM specfile
Fixes build warning:
$ rpmbuild -bs nordugrid-arc.spec
warning: %source_date_epoch_from_changelog is set, but %changelog has no entries to take a date from
Fixes build warning:
$ rpmbuild -bs nordugrid-arc.spec
warning: %source_date_epoch_from_changelog is set, but %changelog has no entries to take a date from