Replace build/tools with build/make/tools

Test: m checkbuild
Change-Id: I8db6c27a6d2372f142d10568fe92d6f2e9a59252
diff --git a/tools/warn.py b/tools/warn.py
index cc63de4..62feac3 100755
--- a/tools/warn.py
+++ b/tools/warn.py
@@ -2371,7 +2371,7 @@
   for idx in reversed(range(2, len(parts))):
     root_path = '/'.join(parts[:idx])
     # Android root directory should contain this script.
-    if os.path.exists(root_path + '/build/tools/warn.py'):
+    if os.path.exists(root_path + '/build/make/tools/warn.py'):
       android_root = root_path
       return root_path
   return ''