MEDIUM: actions: remove ACTION_STOP

Before this patch, two type of custom actions exists: ACT_ACTION_CONT and
ACT_ACTION_STOP. ACT_ACTION_CONT is a non terminal action and ACT_ACTION_STOP is
a terminal action.

Note that ACT_ACTION_STOP is not used in HAProxy.

This patch remove this behavior. Only type type of custom action exists, and it
is called ACT_CUSTOM. Now, the custion action can return a code indicating the
required behavior. ACT_RET_CONT wants that HAProxy continue the current rule
list evaluation, and ACT_RET_STOP wants that HAPRoxy stops the the current rule
list evaluation.
diff --git a/include/types/action.h b/include/types/action.h
index f28cae5..a1dd638 100644
--- a/include/types/action.h
+++ b/include/types/action.h
@@ -34,6 +34,7 @@
 
 enum act_return {
 	ACT_RET_CONT,  /* continue processing. */
+	ACT_RET_STOP,  /* stop processing. */
 	ACT_RET_YIELD, /* call me again. */
 	ACT_RET_ERR,   /* processing error. */
 };
@@ -44,8 +45,7 @@
 };
 
 enum act_name {
-	ACT_ACTION_CONT = 0,
-	ACT_ACTION_STOP,
+	ACT_CUSTOM = 0,
 
 	/* common action */
 	ACT_ACTION_ALLOW,