IGraphicBufferConsumer: fix ATTACH_BUFFER info leak

Bug: 26338113
Change-Id: I019c4df2c6adbc944122df96968ddd11a02ebe33
diff --git a/libs/gui/IGraphicBufferConsumer.cpp b/libs/gui/IGraphicBufferConsumer.cpp
index b86f4c5..c4660ba 100644
--- a/libs/gui/IGraphicBufferConsumer.cpp
+++ b/libs/gui/IGraphicBufferConsumer.cpp
@@ -315,7 +315,7 @@
             CHECK_INTERFACE(IGraphicBufferConsumer, data, reply);
             sp<GraphicBuffer> buffer = new GraphicBuffer();
             data.read(*buffer.get());
-            int slot;
+            int slot = -1;
             int result = attachBuffer(&slot, buffer);
             reply->writeInt32(slot);
             reply->writeInt32(result);