Break a dependency of libui on libandroid

This was only a header dependency, but it still
created a circular dependency, which will cause
problems in another CL.

We fix this by creating a libarect static library
containing only that header. both libui and
libandroid now depend on it and reexport the 
header. 

We also make sure rect.h ends-up in the right
place.

Test: built and booted device
Bug: 35164655

Change-Id: Iba25b8b801b26b26ec1401c00caf367a06f197ca
diff --git a/include/gui/CpuConsumer.h b/include/gui/CpuConsumer.h
index b7aa463..58602bf 100644
--- a/include/gui/CpuConsumer.h
+++ b/include/gui/CpuConsumer.h
@@ -17,18 +17,19 @@
 #ifndef ANDROID_GUI_CPUCONSUMER_H
 #define ANDROID_GUI_CPUCONSUMER_H
 
+#include <system/window.h>
+
 #include <gui/ConsumerBase.h>
+#include <gui/BufferQueue.h>
 
-#include <ui/GraphicBuffer.h>
-
-#include <utils/String8.h>
 #include <utils/Vector.h>
-#include <utils/threads.h>
 
 
 namespace android {
 
 class BufferQueue;
+class GraphicBuffer;
+class String8;
 
 /**
  * CpuConsumer is a BufferQueue consumer endpoint that allows direct CPU