Add 'override' specifier to overridden destructor methods

Test: Build
Bug: 37752547
Change-Id: I157e1c2aa5d9d08fcab6055a3ca48c6ed8a050fc
diff --git a/libs/gui/IGraphicBufferProducer.cpp b/libs/gui/IGraphicBufferProducer.cpp
index 846c205..0149a3f 100644
--- a/libs/gui/IGraphicBufferProducer.cpp
+++ b/libs/gui/IGraphicBufferProducer.cpp
@@ -66,7 +66,7 @@
     {
     }
 
-    virtual ~BpGraphicBufferProducer();
+    ~BpGraphicBufferProducer() override;
 
     virtual status_t requestBuffer(int bufferIdx, sp<GraphicBuffer>* buf) {
         Parcel data, reply;