Queue: use std::swap

src/Queue.cxx

@@ -145,13 +145,10 @@ queue::Append(struct song *song, uint8_t priority)
 void
 queue::SwapPositions(unsigned position1, unsigned position2)
 {
-	struct queue_item tmp;
 	unsigned id1 = items[position1].id;
 	unsigned id2 = items[position2].id;
 
-	tmp = items[position1];
-	items[position1] = items[position2];
-	items[position2] = tmp;
+	std::swap(items[position1], items[position2]);
 
 	items[position1].version = version;
 	items[position2].version = version;

src/Queue.hxx

@@ -24,6 +24,8 @@
 
 #include <glib.h>
 
+#include <algorithm>
+
 #include <assert.h>
 #include <stdint.h>
 
@@ -265,9 +267,7 @@ struct queue {
 	 * Swaps two songs, addressed by their order number.
 	 */
 	void SwapOrders(unsigned order1, unsigned order2) {
-		unsigned tmp = order[order1];
-		order[order1] = order[order2];
-		order[order2] = tmp;
+		std::swap(order[order1], order[order2]);
 	}
 
 	/**