MEDIUM: mworker: proxy for the master CLI

This patch implements a listen proxy within the master. It uses the
sockpair of all the workers as servers.

In the current state of the code, the proxy is only doing round robin on
the CLI of the workers. A CLI mode will be needed to know to which CLI
send the requests.
diff --git a/src/haproxy.c b/src/haproxy.c
index e466904..5affcd2 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1722,6 +1722,11 @@
 			LIST_ADDQ(&proc_list, &tmproc->list);
 		}
 		mworker_env_to_proc_list(); /* get the info of the children in the env */
+
+		if (mworker_cli_proxy_create() < 0) {
+				ha_alert("Can't create the master's CLI.\n");
+				exit(EXIT_FAILURE);
+		}
 	}
 
 	pattern_finalize_config();