MINOR: actions: Add flags to configure the action behaviour

Some flags can now be set on an action when it is registered. The flags are
defined in the act_flag enum. For now, only ACT_FLAG_FINAL may be set on an
action to specify if it stops the rules evaluation. It is set on
ACT_ACTION_ALLOW, ACT_ACTION_DENY, ACT_HTTP_REQ_TARPIT, ACT_HTTP_REQ_AUTH,
ACT_HTTP_REDIR and ACT_TCP_CLOSE actions. But, when required, it may also be set
on custom actions.

Consequently, this flag is checked instead of the action type during the
configuration parsing to trigger a warning when a rule inhibits all the
following ones.
diff --git a/src/tcp_rules.c b/src/tcp_rules.c
index ebf4e05..fae2e15 100644
--- a/src/tcp_rules.c
+++ b/src/tcp_rules.c
@@ -660,14 +660,17 @@
 	if (strcmp(args[arg], "accept") == 0) {
 		arg++;
 		rule->action = ACT_ACTION_ALLOW;
+		rule->flags |= ACT_FLAG_FINAL;
 	}
 	else if (strcmp(args[arg], "reject") == 0) {
 		arg++;
 		rule->action = ACT_ACTION_DENY;
+		rule->flags |= ACT_FLAG_FINAL;
 	}
 	else if (strcmp(args[arg], "close") == 0) {
 		arg++;
 		rule->action = ACT_TCP_CLOSE;
+		rule->flags |= ACT_FLAG_FINAL;
 	}
 	else {
 		struct action_kw *kw;
@@ -721,10 +724,12 @@
 	if (!strcmp(args[arg], "accept")) {
 		arg++;
 		rule->action = ACT_ACTION_ALLOW;
+		rule->flags |= ACT_FLAG_FINAL;
 	}
 	else if (!strcmp(args[arg], "reject")) {
 		arg++;
 		rule->action = ACT_ACTION_DENY;
+		rule->flags |= ACT_FLAG_FINAL;
 	}
 	else if (strcmp(args[arg], "capture") == 0) {
 		struct sample_expr *expr;