Clean up Fence a little.

Test: Cleanup patch only. Fences still work.

Change-Id: I65e5cdf5e3c067bc475c085ab6d3577d9753231c
diff --git a/libs/gui/IGraphicBufferConsumer.cpp b/libs/gui/IGraphicBufferConsumer.cpp
index 2401464..ef770e8 100644
--- a/libs/gui/IGraphicBufferConsumer.cpp
+++ b/libs/gui/IGraphicBufferConsumer.cpp
@@ -19,6 +19,7 @@
 
 #include <utils/Errors.h>
 #include <utils/NativeHandle.h>
+#include <utils/String8.h>
 
 #include <binder/Parcel.h>
 #include <binder/IInterface.h>