LayoutLib: move tests to their own project.

Change-Id: I8a9e128e4a17ab57ec7b126a378035d9ce5bc168
diff --git a/tools/layoutlib/bridge/Android.mk b/tools/layoutlib/bridge/Android.mk
index 7e70f33..687a91f 100644
--- a/tools/layoutlib/bridge/Android.mk
+++ b/tools/layoutlib/bridge/Android.mk
@@ -33,3 +33,6 @@
 
 include $(BUILD_HOST_JAVA_LIBRARY)
 
+# Build all sub-directories
+include $(call all-makefiles-under,$(LOCAL_PATH))
+