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/opengl/libagl/egl.cpp b/opengl/libagl/egl.cpp
index 48bf676..04f6d6d 100644
--- a/opengl/libagl/egl.cpp
+++ b/opengl/libagl/egl.cpp
@@ -33,6 +33,7 @@
 #include <ui/ANativeObjectBase.h>
 #include <ui/Fence.h>
 #include <ui/GraphicBufferMapper.h>
+#include <ui/Rect.h>
 
 #include <EGL/egl.h>
 #include <EGL/eglext.h>