Add GraphicBuffer over binder test and fix a crash in unflatten logic

Test: GraphicBuffer_test GraphicBufferOverBinder_test
Bug: None
Change-Id: Idf00fcb740661adc1e1bb41dc2d78ece4f589c95
diff --git a/libs/ui/GraphicBuffer.cpp b/libs/ui/GraphicBuffer.cpp
index 3fc6a2d..579e68e 100644
--- a/libs/ui/GraphicBuffer.cpp
+++ b/libs/ui/GraphicBuffer.cpp
@@ -626,7 +626,7 @@
                            bufferHubBuffer->desc().layers, bufferHubBuffer->desc().usage,
                            bufferHubBuffer->desc().stride);
     mBufferId = bufferHubBuffer->id();
-    mBufferHubBuffer.reset(std::move(bufferHubBuffer.get()));
+    mBufferHubBuffer = std::move(bufferHubBuffer);
 
     return NO_ERROR;
 }