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/vr/libsensor/Android.mk b/libs/vr/libsensor/Android.mk
index 8c7ad43..89abcb0 100644
--- a/libs/vr/libsensor/Android.mk
+++ b/libs/vr/libsensor/Android.mk
@@ -32,6 +32,7 @@
 	libhardware \
 	liblog \
 	libutils \
+	libandroid \
 
 include $(CLEAR_VARS)
 LOCAL_SRC_FILES := $(sourceFiles)