Append linux to the Linux OMERO clients

Fixes https://trac.openmicroscopy.org.uk/ome/ticket/12187

To test this PR, 
- check the Insight insight is now appended with `-linux`
- check the Insight clients package is appended with `.linux`
- check the clients for the other platforms are unaffected by these changes

It's okay to lose the hyphen in this matching?