Drop unused imports from leftovers (pytorch#49953)

Summary:
Pull Request resolved: pytorch#49953

From
```
./python/libcst/libcst codemod remove_unused_imports.RemoveUnusedImportsWithGlean --no-format caffe2/
```

Test Plan: Standard sandcastle tests

Reviewed By: xush6528

Differential Revision: D25727348

fbshipit-source-id: b3feef80b9b4b535f1bd4060dace5b1a50bd5e69

setup.py

@@ -186,7 +186,7 @@
                                                                      python_min_version_str))
     sys.exit(-1)
 
-from setuptools import setup, Extension, distutils, find_packages
+from setuptools import setup, Extension, find_packages
 from collections import defaultdict
 from distutils import core
 from distutils.core import Distribution

tools/setup_helpers/cmake.py

@@ -7,7 +7,6 @@
 import re
 from subprocess import check_call, check_output
 import sys
-import distutils
 import distutils.sysconfig
 from distutils.version import LooseVersion