libcore_to_document and junit_to_document are no longer functions.

They are evaluated only once in the corresponding export .mk file.
This fixes build log spam reported in:
https://code.google.com/p/android/issues/detail?id=63184

Change-Id: I549eb052272bbdebef8fca697822f5eaa0fe5764
diff --git a/tests/TileBenchmark/Android.mk b/tests/TileBenchmark/Android.mk
index 5851113..9a057af 100644
--- a/tests/TileBenchmark/Android.mk
+++ b/tests/TileBenchmark/Android.mk
@@ -17,7 +17,7 @@
 
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_SRC_FILES := $(call all-java-files-under, src)
+LOCAL_SRC_FILES :=
 
 LOCAL_PACKAGE_NAME := TileBenchmark
 
@@ -25,4 +25,4 @@
 
 LOCAL_JAVA_LIBRARIES := android.test.runner
 
-include $(BUILD_PACKAGE)
\ No newline at end of file
+include $(BUILD_PACKAGE)