Fix support of NSS after ECDSA addition
Fix support of NSS after ECDSA addition

Fix compiler error:
cert_vfy.c: At top level:
cert_vfy.c:44:5: error: conflicting types for ‘verify_signature’
 int verify_signature(X509 * x509, unsigned char *data, int data_length,
     ^~~~~~~~~~~~~~~~
In file included from cert_vfy.c:18:0:
cert_vfy.h:81:20: note: previous declaration of ‘verify_signature’ was here
 CERTVFY_EXTERN int verify_signature(X509 * x509, unsigned char *data, int data_length, unsigned char **signature, int *signature_length);
                    ^~~~~~~~~~~~~~~~

OpenSC/pam_pkcs11,OpenSC/pam_pkcs11