Increase listen backlog for gloo

Summary:
The backlog argument defines the maximum length to which the queue of pending connections for sockfd may grow. If we exceed the backlog, clients will get a RST (with our in-house setting of net.ipv4.tcp_abort_on_overflow = 1)

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: xunnanxu

Differential Revision: D45134876

fbshipit-source-id: 7236281f8027ccebbbf92345ec7752a18ae1278d

gloo/transport/tcp/pair.cc

@@ -178,7 +178,7 @@ void Pair::listen() {
 
   // listen(2) on socket
   fd_ = fd;
-  rv = ::listen(fd_, 1);
+  rv = ::listen(fd_, 1024);
   if (rv == -1) {
     ::close(fd_);
     fd_ = FD_INVALID;