This patch allows compile time define for listen backlog.
Defaults to previous behaviour: 5

--- fcgi-2.4.0/cgi-fcgi/cgi-fcgi.c~	2001-09-01 03:14:28.000000000 +0200
+++ fcgi-2.4.0/cgi-fcgi/cgi-fcgi.c	2005-05-09 18:09:17.000000000 +0300
@@ -52,6 +52,9 @@
 #include "fastcgi.h"
 #include "fcgios.h"
 
+#ifndef LISTEN_BACKLOG
+#define LISTEN_BACKLOG 5
+#endif
 
 static int wsReadPending = 0;
 static int fcgiReadPending = 0;
@@ -514,7 +517,7 @@
     int listenFd, i;
 
     /* @@@ Should be able to pick up the backlog as an arg */
-    if((listenFd = OS_CreateLocalIpcFd(bindPath, 5)) == -1) {
+    if((listenFd = OS_CreateLocalIpcFd(bindPath, LISTEN_BACKLOG)) == -1) {
         exit(OS_Errno);
     }