depends gmp &&
  optional_depends curl     '--enable-http'  \
                            '' \
                            'fetch Certificates and CRLs via http'  &&
  optional_depends openldap '--enable-ldap'  \
                            '' \
                            'fetch CRLs from LDAP'   &&
  optional_depends opensc   '--enable-smartcard'  \
                            '' \
                            'enable smartcard support'
