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/services/surfaceflinger/Android.mk b/services/surfaceflinger/Android.mk
index 9e81a8c..ec47c8a 100644
--- a/services/surfaceflinger/Android.mk
+++ b/services/surfaceflinger/Android.mk
@@ -206,6 +206,7 @@
     liblog \
     libbinder \
     libutils \
+    libui \
     libdl
 
 LOCAL_WHOLE_STATIC_LIBRARIES := libsigchain