MINOR: server: move idle_conn_task to read_mostly
This pointer is used when adding connections to the idle list and is
never changed, let's move it to the read_mostly section.
diff --git a/src/server.c b/src/server.c
index 9043a77..3f05904 100644
--- a/src/server.c
+++ b/src/server.c
@@ -66,7 +66,7 @@
__decl_thread(HA_SPINLOCK_T idle_conn_srv_lock);
struct eb_root idle_conn_srv = EB_ROOT;
-struct task *idle_conn_task = NULL;
+struct task *idle_conn_task __read_mostly = NULL;
struct list servers_list = LIST_HEAD_INIT(servers_list);
/* The server names dictionary */