hle: nvflinger: consumer_base: StillTracking: Should be const.

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

@@ -117,7 +117,8 @@ Status ConsumerBase::ReleaseBufferLocked(s32 slot,
     return err;
 }
 
-bool ConsumerBase::StillTracking(s32 slot, const std::shared_ptr<GraphicBuffer> graphic_buffer) {
+bool ConsumerBase::StillTracking(s32 slot,
+                                 const std::shared_ptr<GraphicBuffer> graphic_buffer) const {
     if (slot < 0 || slot >= BufferQueueDefs::NUM_BUFFER_SLOTS) {
         return false;
     }

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

@@ -38,7 +38,7 @@ protected:
     Status AcquireBufferLocked(BufferItem* item, std::chrono::nanoseconds present_when,
                                u64 max_frame_number = 0);
     Status ReleaseBufferLocked(s32 slot, const std::shared_ptr<GraphicBuffer> graphic_buffer);
-    bool StillTracking(s32 slot, const std::shared_ptr<GraphicBuffer> graphic_buffer);
+    bool StillTracking(s32 slot, const std::shared_ptr<GraphicBuffer> graphic_buffer) const;
     Status AddReleaseFenceLocked(s32 slot, const std::shared_ptr<GraphicBuffer> graphic_buffer,
                                  const Fence& fence);