tls: fix error ssl socket support

Check of ssl socket support occurs always, even if ssl is disabled.

After the patch support of ssl socket checks only if tls is enabled.

http/server.lua

@@ -1393,7 +1393,7 @@ local function validate_ssl_opts(opts)
         error("ssl_key_file and ssl_cert_file must be set to enable TLS")
     end
 
-    if not sslsocket_supported then
+    if is_tls_enabled and not sslsocket_supported then
         error("ssl socket is not supported")
     end