Adjust for changes to libcore/Docs.mk

The paths in libcore_to_document are now relative to
the build root, not libcore.

Bug: 22023363
Change-Id: I75c86d6332e5eaedc67dd0d3207491aa91c02a5f
diff --git a/Android.mk b/Android.mk
index 7df1bd7..932723b 100644
--- a/Android.mk
+++ b/Android.mk
@@ -679,7 +679,7 @@
 # Common sources for doc check and api check
 common_src_files := \
 	$(call find-other-html-files, $(html_dirs)) \
-	$(addprefix ../../libcore/, $(libcore_to_document)) \
+	$(addprefix ../../, $(libcore_to_document)) \
 	$(addprefix ../../external/junit/, $(junit_to_document))
 
 # These are relative to frameworks/base