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/libs/ui/GraphicBufferMapper.cpp b/libs/ui/GraphicBufferMapper.cpp
index a3b6e18..f418f7f 100644
--- a/libs/ui/GraphicBufferMapper.cpp
+++ b/libs/ui/GraphicBufferMapper.cpp
@@ -35,7 +35,7 @@
 #include <ui/Gralloc1On0Adapter.h>
 #include <ui/GrallocMapper.h>
 #include <ui/GraphicBufferMapper.h>
-#include <ui/Rect.h>
+#include <ui/GraphicBuffer.h>
 
 #include <system/graphics.h>