bpo-40683: Add zoneinfo to LIBSUBDIRS (#20229)

Without this, only the _zoneinfo module is getting installed, not the
zoneinfo module. I believe this was not noticed earlier because
test.test_zoneinfo was also not being installed.
diff --git a/Makefile.pre.in b/Makefile.pre.in
index de50f6b..5a18704 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1429,6 +1429,7 @@
 		test/test_importlib/source \
 		test/test_importlib/zipdata01 \
 		test/test_importlib/zipdata02 \
+		test/test_zoneinfo test/test_zoneinfo/data \
 		test/ziptestdata \
 		asyncio \
 		test/test_asyncio \
@@ -1450,7 +1451,8 @@
 		multiprocessing multiprocessing/dummy \
 		unittest unittest/test unittest/test/testmock \
 		venv venv/scripts venv/scripts/common venv/scripts/posix \
-		curses pydoc_data
+		curses pydoc_data \
+		zoneinfo
 libinstall:	build_all $(srcdir)/Modules/xxmodule.c
 	@for i in $(SCRIPTDIR) $(LIBDEST); \
 	do \
diff --git a/Misc/NEWS.d/next/Build/2020-05-19-10-54-08.bpo-40683.W8JHrr.rst b/Misc/NEWS.d/next/Build/2020-05-19-10-54-08.bpo-40683.W8JHrr.rst
new file mode 100644
index 0000000..d57e064
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2020-05-19-10-54-08.bpo-40683.W8JHrr.rst
@@ -0,0 +1,2 @@
+Fixed an issue where the :mod:`zoneinfo` module and its tests were not
+included when Python is installed with ``make``.