[freepats] Fixed broken links for a few sound banks

[Roberto]

I've received an email reporting broken links for synth strings #2 and
clarinet, they should be working now.

There were thousands of visitors trying to download those sound banks,
and thousands of 404 errors returned by the server, but nobody reported
the problem until today.

Quite probably, I'll continue adding a few mistakes from time to time,
we are doing FreePats in our free time and usually things are made in a
hurry. Sending feedback takes time and it's understandable that not
everyone feels inclined, but it is much appreciated, it make us aware of
mistakes and helps to improve things.