Remove obsolete error constant CT_F_CTLOG_NEW_NULL

ctlog_new_null() no longer exists.
Reviewed-by: NViktor Dukhovni <viktor@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1554)

include/openssl/ct.h

@@ -482,7 +482,6 @@ int ERR_load_CT_strings(void);
 # define CT_F_CTLOG_NEW                                   117
 # define CT_F_CTLOG_NEW_FROM_BASE64                       118
 # define CT_F_CTLOG_NEW_FROM_CONF                         119
-# define CT_F_CTLOG_NEW_NULL                              120
 # define CT_F_CTLOG_STORE_LOAD_CTX_NEW                    122
 # define CT_F_CTLOG_STORE_LOAD_FILE                       123
 # define CT_F_CTLOG_STORE_LOAD_LOG                        130