pillow fight needs truststorepath set to use self-signed certificates

See https://www.couchbase.com/forums/t/c-sdk-3-3-1-tls-authentification-doesnt-work-with-the-couchbase-server-enterprise-7-1-3-image/36185

And putting the server certificate in certpath as described in the documention doesn't seem to work.

./libcouchbase/doc/man/cbc-pillowfight.1:\fBcertpath=PATH\fR: The path to the server\'s SSL certificate\. This is typically required for SSL connectivity unless the certificate has already been added to the OpenSSL installation on the system (only applicable with \fBcouchbases://\fR scheme)\. This also should contain client certificate when certificate authentication used, and in this case other public certificates could be extracted into \fBtruststorepath\fR chain\.

I don't find any mention of truststorepath in the C SDK documentation - it seems to have disappeared after 3.0.7.