Revert "Revert "Use the Finder's results for faster searching""

This reverts commit 6f2aea5636e62197c7938073ee52dace620e03c5.

Reason for revert: Fix went in ( I70b08023b94b5789dc8394651bbac4c49c82787f ); trying again to use this

Change-Id: I0f58c21a7312dda01980d338401e756f610fe3b4
diff --git a/core/cleanspec.mk b/core/cleanspec.mk
index 4441e2a..af28954 100644
--- a/core/cleanspec.mk
+++ b/core/cleanspec.mk
@@ -64,6 +64,6 @@
 # ************************************************
 
 subdir_cleanspecs := \
-    $(shell build/tools/findleaves.py $(FIND_LEAVES_EXCLUDES) . CleanSpec.mk)
+    $(file <$(OUT_DIR)/.module_paths/CleanSpec.mk.list)
 include $(subdir_cleanspecs)
 subdir_cleanspecs :=