MINOR: http-rules: Add more return codes to let custom actions act as normal ones

When HTTP/TCP rules are evaluated, especially HTTP ones, some results are
possible for normal actions and not for custom ones. So missing return codes
(ACT_RET_) have been added to let custom actions act as normal ones. Concretely
following codes have been added:

 * ACT_RET_DENY : deny the request/response. It must be handled by the caller
 * ACT_RET_ABRT : abort the request/response, handled by action itsleft.
 * ACT_RET_INV  : invalid request/response
diff --git a/include/types/action.h b/include/types/action.h
index 516ffdd..33dcd51 100644
--- a/include/types/action.h
+++ b/include/types/action.h
@@ -37,11 +37,14 @@
 };
 
 enum act_return {
-	ACT_RET_CONT,  /* continue processing. */
-	ACT_RET_STOP,  /* stop processing. */
-	ACT_RET_YIELD, /* call me again. */
-	ACT_RET_ERR,   /* processing error. */
-	ACT_RET_DONE,  /* processing done, stop processing */
+	ACT_RET_CONT,   /* continue processing. */
+	ACT_RET_STOP,   /* stop processing. */
+	ACT_RET_YIELD,  /* call me again. */
+	ACT_RET_ERR,    /* internal processing error. */
+	ACT_RET_DONE,   /* processing done, stop processing */
+	ACT_RET_DENY,   /* deny, must be handled by the caller */
+	ACT_RET_ABRT,   /* abort, handled by action itsleft. */
+	ACT_RET_INV,    /* invalid request/response */
 };
 
 enum act_parse_ret {