Close the listen sockets in child processes

By keeping the listen sockets open, the children were preventing the
daemon from being restarted cleanly. Once the child has forked these
listen sockets are no longer needed by that process, so can be closed.

postsrsd.c

         conn = accept(fds[i].fd, NULL, NULL);
         if (conn < 0) continue;
         if (fork() == 0) {
+          // close listen sockets so that we don't stop the main daemon process from restarting
+          close(forward_sock);
+          close(reverse_sock);
+
           fp = fdopen(conn, "r+");
           if (fp == NULL) exit(EXIT_FAILURE);
           fds[2].fd = conn;