Don't catch SIGCHLD in libvirtd

libvirtd no longer deals with SIGCHLD in its signal handler
since the QEMU driver switched to always daemonize processes.
Thus remove the sigaction for it, to avoid warning log
messages

* daemon/libvirtd.c: Don't catch SIGCHLD

daemon/libvirtd.c

@@ -2973,7 +2973,6 @@ daemonSetupSignals(struct qemud_server *server)
     sigaction(SIGINT, &sig_action, NULL);
     sigaction(SIGQUIT, &sig_action, NULL);
     sigaction(SIGTERM, &sig_action, NULL);
-    sigaction(SIGCHLD, &sig_action, NULL);
 
     sig_action.sa_handler = SIG_IGN;
     sigaction(SIGPIPE, &sig_action, NULL);