MINOR: action: Add function to check rules using an action ACT_ACTION_TRK_*

The function "check_trk_action" has been added to find and check the target
table for rules using an action ACT_ACTION_TRK_*.
diff --git a/include/proto/action.h b/include/proto/action.h
index ce94aa0..e3015ec 100644
--- a/include/proto/action.h
+++ b/include/proto/action.h
@@ -76,4 +76,12 @@
 	return trk_action - ACT_ACTION_TRK_SC0;
 }
 
+/* Find and check the target table used by an action ACT_ACTION_TRK_*. This
+ * function should be called during the configuration validity check.
+ *
+ * The function returns 1 in success case, otherwise, it returns 0 and err is
+ * filled.
+ */
+int check_trk_action(struct act_rule *rule, struct proxy *px, char **err);
+
 #endif /* _PROTO_ACTION_H */