Fix build for package_data

Summary: include_package_data does not work well in the presence of built extensions, and the OSS build hasn't been working for a few days since #593 was merged.

Reviewed By: patricklabatut

Differential Revision: D29302315

fbshipit-source-id: db7e46f8c4593743c3522087979592f9989c7c6b

MANIFEST.in

-include pytorch3d/datasets/shapenet/shapenet_synset_dict_v1.json
-include pytorch3d/datasets/shapenet/shapenet_synset_dict_v2.json
-include pytorch3d/datasets/r2n2/r2n2_synset_dict.json

setup.py

@@ -146,5 +146,7 @@ setup(
     },
     ext_modules=get_extensions(),
     cmdclass={"build_ext": BuildExtension},
-    include_package_data=True,
+    package_data={
+        "": ["*.json"],
+    },
 )