Provide a function to send a KeyUpdate message

This implements the server side KeyUpdate sending capability as well.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2609)

ssl/ssl_err.c

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index cea6040..2d9efbb 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -179,6 +179,7 @@
     {ERR_FUNC(SSL_F_SSL_GET_SERVER_CERT_INDEX), "ssl_get_server_cert_index"},
     {ERR_FUNC(SSL_F_SSL_GET_SIGN_PKEY), "ssl_get_sign_pkey"},
     {ERR_FUNC(SSL_F_SSL_INIT_WBIO_BUFFER), "ssl_init_wbio_buffer"},
+    {ERR_FUNC(SSL_F_SSL_KEY_UPDATE), "SSL_key_update"},
     {ERR_FUNC(SSL_F_SSL_LOAD_CLIENT_CA_FILE), "SSL_load_client_CA_file"},
     {ERR_FUNC(SSL_F_SSL_LOG_MASTER_SECRET), "ssl_log_master_secret"},
     {ERR_FUNC(SSL_F_SSL_LOG_RSA_CLIENT_KEY_EXCHANGE),
@@ -201,6 +202,7 @@
     {ERR_FUNC(SSL_F_SSL_PEEK_EX), "SSL_peek_ex"},
     {ERR_FUNC(SSL_F_SSL_READ), "SSL_read"},
     {ERR_FUNC(SSL_F_SSL_READ_EX), "SSL_read_ex"},
+    {ERR_FUNC(SSL_F_SSL_RENEGOTIATE), "SSL_renegotiate"},
     {ERR_FUNC(SSL_F_SSL_SCAN_CLIENTHELLO_TLSEXT),
      "ssl_scan_clienthello_tlsext"},
     {ERR_FUNC(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT),
@@ -333,6 +335,7 @@
      "tls_construct_hello_request"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_HELLO_RETRY_REQUEST),
      "tls_construct_hello_retry_request"},
+    {ERR_FUNC(SSL_F_TLS_CONSTRUCT_KEY_UPDATE), "tls_construct_key_update"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_NEW_SESSION_TICKET),
      "tls_construct_new_session_ticket"},
     {ERR_FUNC(SSL_F_TLS_CONSTRUCT_NEXT_PROTO), "tls_construct_next_proto"},
@@ -568,6 +571,7 @@
      "invalid configuration name"},
     {ERR_REASON(SSL_R_INVALID_CT_VALIDATION_TYPE),
      "invalid ct validation type"},
+    {ERR_REASON(SSL_R_INVALID_KEY_UPDATE_TYPE), "invalid key update type"},
     {ERR_REASON(SSL_R_INVALID_NULL_CMD_NAME), "invalid null cmd name"},
     {ERR_REASON(SSL_R_INVALID_SEQUENCE_NUMBER), "invalid sequence number"},
     {ERR_REASON(SSL_R_INVALID_SERVERINFO_DATA), "invalid serverinfo data"},
@@ -715,6 +719,7 @@
     {ERR_REASON(SSL_R_SSL_SESSION_ID_TOO_LONG), "ssl session id too long"},
     {ERR_REASON(SSL_R_SSL_SESSION_VERSION_MISMATCH),
      "ssl session version mismatch"},
+    {ERR_REASON(SSL_R_STILL_IN_INIT), "still in init"},
     {ERR_REASON(SSL_R_TLSV1_ALERT_ACCESS_DENIED),
      "tlsv1 alert access denied"},
     {ERR_REASON(SSL_R_TLSV1_ALERT_DECODE_ERROR), "tlsv1 alert decode error"},