gutenprint: fixes around genppd

• in papers.xml, rename "Greeting Card" paper format names to not contain decimal points ("."), as gutenprint's internal list handling rejects points in element names. I guess these paper formats never really worked, but I can't really test this for lack of a supported printer.
• create symlink cups-genppd to cups.genppd.5.2 to match documentation.

PR: 226863 226865
Reported by: freebsd dreamchaser org