fix needed for FELIX-6204: org.apache.felix.scrplugin.helper.ClassScanner.scanSources should ignore module-info

[Julian Reschke]

Hi Felix experts,

please see <https://issues.apache.org/jira/browse/FELIX-6204>. We need
this in Jackrabbit Oak because new versions of Jackson include module-info.

A PR is attached to the ticket.

Best regards, Julian