openssl: fix the libressl build again

Follow-up to 84fcaa2e7. libressl does not have the API even if it says it is
late OpenSSL version...

Fixes #2246
Closes #2247

Reported-by: jungle-boogie on github

lib/vtls/openssl.c

@@ -259,7 +259,7 @@ static void tap_ssl_key(const SSL *ssl, ssl_tap_state_t *state)
   if(!session || !keylog_file_fp)
     return;
 
-#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
   /* ssl->s3 is not checked in openssl 1.1.0-pre6, but let's assume that
    * we have a valid SSL context if we have a non-NULL session. */
   SSL_get_client_random(ssl, client_random, SSL3_RANDOM_SIZE);