Adds new method for rule merge

IMPORTANT: SecDefaultAction specified on a child configuration will
overwrite the ones specified on the parent; Previously it was
concatenating.

headers/modsecurity/rule_unconditional.h

@@ -46,7 +46,11 @@ class RuleUnconditional : public RuleWithActions {
         int lineNumber)
         : RuleWithActions(actions, transformations, std::move(fileName), lineNumber) { }
 
-    virtual bool evaluate(Transaction *transaction, std::shared_ptr<RuleMessage> ruleMessage) override;
+    RuleUnconditional(const RuleUnconditional &r)
+        : RuleWithActions(r)
+        { }
+
+    virtual bool evaluate(Transaction *transaction) override;
 
  private:
 };