Implement TLSv1.3 style CertificateStatus

We remove the separate CertificateStatus message for TLSv1.3, and instead
send back the response in the appropriate Certificate message extension.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2020)

ssl/ssl_err.c

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index 1b3e409..5685817 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -92,6 +92,7 @@
     {ERR_FUNC(SSL_F_SSL3_WRITE_PENDING), "ssl3_write_pending"},
     {ERR_FUNC(SSL_F_SSL_ADD_CERT_CHAIN), "ssl_add_cert_chain"},
     {ERR_FUNC(SSL_F_SSL_ADD_CERT_TO_BUF), "ssl_add_cert_to_buf"},
+    {ERR_FUNC(SSL_F_SSL_ADD_CERT_TO_WPACKET), "ssl_add_cert_to_wpacket"},
     {ERR_FUNC(SSL_F_SSL_ADD_CLIENTHELLO_RENEGOTIATE_EXT),
      "ssl_add_clienthello_renegotiate_ext"},
     {ERR_FUNC(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT),
@@ -259,6 +260,8 @@
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST),
      "tls_construct_certificate_request"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CERT_STATUS), "tls_construct_cert_status"},
+    {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CERT_STATUS_BODY),
+     "tls_construct_cert_status_body"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CHANGE_CIPHER_SPEC),
      "tls_construct_change_cipher_spec"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_CKE_DHE), "tls_construct_cke_dhe"},
@@ -373,6 +376,8 @@
     {ERR_FUNC(SSL_F_TLS_PROCESS_CERTIFICATE_REQUEST),
      "tls_process_certificate_request"},
     {ERR_FUNC(SSL_F_TLS_PROCESS_CERT_STATUS), "tls_process_cert_status"},
+    {ERR_FUNC(SSL_F_TLS_PROCESS_CERT_STATUS_BODY),
+     "tls_process_cert_status_body"},
     {ERR_FUNC(SSL_F_TLS_PROCESS_CERT_VERIFY), "tls_process_cert_verify"},
     {ERR_FUNC(SSL_F_TLS_PROCESS_CHANGE_CIPHER_SPEC),
      "tls_process_change_cipher_spec"},