deps: upgrade libuv to dc559a5

deps/uv/src/unix/tcp.c

@@ -233,7 +233,7 @@ int uv_tcp_listen(uv_tcp_t* tcp, int backlog, uv_connection_cb cb) {
 
   if (single_accept == -1) {
     const char* val = getenv("UV_TCP_SINGLE_ACCEPT");
-    single_accept = (val == NULL) || (atoi(val) != 0); /* on by default */
+    single_accept = (val != NULL && atoi(val) != 0);  /* Off by default. */
   }
 
   if (single_accept)