Include test_tools and test_warnings in install

test_tools is pretty much useless unless somebody copies the scripts
it tests into the proper location, but we might as well install it
anyway to make sure it skips properly.  test_warnings just didn't get
included when it was turned into a package in 94966dfd3bd3.

Makefile.pre.in

@@ -1221,6 +1221,7 @@ LIBSUBDIRS=	tkinter tkinter/test tkinter/test/test_tkinter \
 		importlib test/test_importlib test/test_importlib/builtin \
 		test/test_importlib/extension test/test_importlib/frozen \
 		test/test_importlib/import_ test/test_importlib/source \
+		test/test_tools test/test_warnings \
 		turtledemo \
 		multiprocessing multiprocessing/dummy \
 		unittest unittest/test unittest/test/testmock \