Cause buildtools to raise a DeprecationWarning.
diff --git a/Lib/plat-mac/buildtools.py b/Lib/plat-mac/buildtools.py
index c83e218..f5dab88 100644
--- a/Lib/plat-mac/buildtools.py
+++ b/Lib/plat-mac/buildtools.py
@@ -14,6 +14,9 @@
 import EasyDialogs
 import shutil
 
+import warnings
+warnings.warn("the buildtools module is deprecated", DeprecationWarning, 2)
+
 
 BuildError = "BuildError"