title: HTTPS connection with no client certificate using mbedTLS
body: <p>I need (because I was told to) to connect to an endpoint that ends up at gooogleapis.com without having a client certificate. RFC5246 says this is possible:</p>
  
  <p>If no suitable certificate is available,
        the client MUST send a certificate message containing no
        certificates.  That is, the certificate_list structure has a
        length of zero.</p>
  
  <p>But I have no idea how this can be done. I'm using mbedTLS 2.13.1 in an embedded system. The single example code I have uses a client certificate, and mbedTLS has no documentation about how to do otherwise.</p>