In the SWT fragment jars published in the Eclipse p2-repository the
localization files had the wrong names, which are used at dev-time to
avoid localization when launching SWT from a development environment.

Furthermore the 'swt.jar' is now not modified anymore before adding it
to the assembly for the download-page, which ensures intact signatures.

Fixes https://github.com/eclipse-platform/eclipse.platform.releng.aggregator/issues/2189