Make internal signalfd close on exec

src/liblwevent/400_signalfd.c

@@ -63,7 +63,7 @@ struct lwevent_signal* lwevent_signalfd(const sigset_t* mask, lwevent_signalcb c
         return 0;
     }
 
-    if(lwevent_nonblock(fd)) {
+    if(lwevent_nonblock(fd) || lwevent_cloexec(fd)) {
         TEMP_FAILURE_RETRY( close(fd) );
         free(si);
         return 0;