Since commit 04a5a44 ("BUILD: ssl: use HAVE_OPENSSL_KEYLOG instead of OpenSSL versions") the "tune.ssl.keylog" feature is broken because HAVE_OPENSSL_KEYLOG does not exist. Replace this by a HAVE_SSL_KEYLOG which is defined in openssl-compat.h. Also add an error when not built with the right openssl version. Must be backported as far as 2.3.