util/IntrusiveList: add reverse_iterator

src/util/IntrusiveList.hxx

@@ -412,6 +412,16 @@ public:
 		return {&ToNode(t)};
 	}
 
+	using reverse_iterator = std::reverse_iterator<iterator>;
+
+	constexpr reverse_iterator rbegin() noexcept {
+		return reverse_iterator{end()};
+	}
+
+	constexpr reverse_iterator rend() noexcept {
+		return reverse_iterator{begin()};
+	}
+
 	class const_iterator final {
 		friend IntrusiveList;
 
@@ -487,6 +497,16 @@ public:
 		return {&ToNode(t)};
 	}
 
+	using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+	constexpr const_reverse_iterator rbegin() const noexcept {
+		return reverse_iterator{end()};
+	}
+
+	constexpr const_reverse_iterator rend() const noexcept {
+		return reverse_iterator{begin()};
+	}
+
 	/**
 	 * @return an iterator to the item following the specified one
 	 */