buffer_item_consumer: Pass fence by const-ref in ReleaseBuffer()

This isn't directly modified.

Also allows rvalues to be used with it.

src/core/hle/service/nvflinger/buffer_item_consumer.cpp

@@ -39,7 +39,7 @@ Status BufferItemConsumer::AcquireBuffer(BufferItem* item, std::chrono::nanoseco
     return Status::NoError;
 }
 
-Status BufferItemConsumer::ReleaseBuffer(const BufferItem& item, Fence& release_fence) {
+Status BufferItemConsumer::ReleaseBuffer(const BufferItem& item, const Fence& release_fence) {
     std::scoped_lock lock{mutex};
 
     if (const auto status = AddReleaseFenceLocked(item.buf, item.graphic_buffer, release_fence);

src/core/hle/service/nvflinger/buffer_item_consumer.h

@@ -22,7 +22,7 @@ public:
     explicit BufferItemConsumer(std::unique_ptr<BufferQueueConsumer> consumer);
     Status AcquireBuffer(BufferItem* item, std::chrono::nanoseconds present_when,
                          bool wait_for_fence = true);
-    Status ReleaseBuffer(const BufferItem& item, Fence& release_fence);
+    Status ReleaseBuffer(const BufferItem& item, const Fence& release_fence);
 };
 
 } // namespace Service::android

src/core/hle/service/nvflinger/nvflinger.cpp

@@ -307,8 +307,7 @@ void NVFlinger::Compose() {
 
         swap_interval = buffer.swap_interval;
 
-        auto fence = android::Fence::NoFence();
-        layer.GetConsumer().ReleaseBuffer(buffer, fence);
+        layer.GetConsumer().ReleaseBuffer(buffer, android::Fence::NoFence());
     }
 }