allow to set listen options in any server

src/http/ngx_http.c

diff --git a/src/http/ngx_http.c b/src/http/ngx_http.c
index 15b53fe..44166a4 100644
--- a/src/http/ngx_http.c
+++ b/src/http/ngx_http.c
@@ -1209,6 +1209,12 @@
             return NGX_ERROR;
         }
 
+        if (lsopt->set && addr[i].opt.set) {
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                        "a duplicate listen options for %s", addr[i].opt.addr);
+            return NGX_ERROR;
+        }
+
         /* check the duplicate "default" server for this address:port */
 
         if (lsopt->default_server) {