Enable more golangci-lint linters on Cirrus

Currently, [some Go linters](https://github.com/namecoin/pkcs11mod/blob/6f875e1723e305e84f1a217be4b5acd7390c3858/.cirrus.yml#L188-L190) are marked as non-mandatory, because we'd like to pass them but we don't right now.  It would be desirable to fix whatever failures they trigger, and then enable them as mandatory.