CLEANUP: tcp rules: mention everywhere that tcp-conn rules are L4

This is in order to make integration of tcp-request-session cleaner :
- tcp_exec_req_rules() was renamed tcp_exec_l4_rules()
- LI_O_TCP_RULES was renamed LI_O_TCP_L4_RULES
  (LI_O_*'s horrible indent was also fixed and a provision was left
   for L5 rules).
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 7b58ef6..17f9d19 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -8828,7 +8828,7 @@
 			listener->default_target = curproxy->default_target;
 
 			if (!LIST_ISEMPTY(&curproxy->tcp_req.l4_rules))
-				listener->options |= LI_O_TCP_RULES;
+				listener->options |= LI_O_TCP_L4_RULES;
 
 			if (curproxy->mon_mask.s_addr)
 				listener->options |= LI_O_CHK_MONNET;