Move Certificate Verify construction and processing into statem_lib.c

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2157)

ssl/ssl_err.c

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index 5685817..9f075e7 100644
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -262,6 +262,7 @@
     {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_CERT_VERIFY), "tls_construct_cert_verify"},
     {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"},