THRIFT-4029: add MANIFEST.in to include the extension files
Client: py

This closes #1206
diff --git a/lib/py/MANIFEST.in b/lib/py/MANIFEST.in
new file mode 100644
index 0000000..af54e29
--- /dev/null
+++ b/lib/py/MANIFEST.in
@@ -0,0 +1 @@
+include src/ext/*