Remove more unused imports in tests.

Lib/ctypes/test/test_bitfields.py

@@ -3,7 +3,6 @@ from ctypes.test import need_symbol
 import unittest
 import os
 
-import ctypes
 import _ctypes_test
 
 class BITS(Structure):

Lib/ctypes/test/test_pep3118.py

 import unittest
 from ctypes import *
-import re, struct, sys
+import re, sys
 
 if sys.byteorder == "little":
     THIS_ENDIAN = "<"

Lib/lib2to3/tests/support.py

@@ -3,10 +3,8 @@
 
 # Python imports
 import unittest
-import sys
 import os
 import os.path
-import re
 from textwrap import dedent
 
 # Local imports

Lib/test/eintrdata/eintr_tester.py

@@ -10,7 +10,6 @@ sub-second periodicity (contrarily to signal()).
 
 import contextlib
 import faulthandler
-import io
 import os
 import select
 import signal

Lib/test/test_eintr.py

 import os
 import signal
-import subprocess
 import unittest
 
 from test import support

Lib/test/test_imp.py

@@ -6,7 +6,6 @@ import importlib
 import importlib.util
 import os
 import os.path
-import shutil
 import sys
 from test import support
 import unittest

Lib/test/test_json/test_fail.py

 from test.test_json import PyTest, CTest
-import re
 
 # 2007-10-05
 JSONDOCS = [

Lib/test/test_subprocess.py

 import unittest
-from test.support import script_helper
 from test import support
 import subprocess
 import sys

Lib/test/test_symbol.py

 import unittest
 from test import support
-import filecmp
 import os
 import sys
 import subprocess

Lib/test/test_threading.py

@@ -7,7 +7,6 @@ from test.support import verbose, import_module, cpython_only
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
 import random
-import re
 import sys
 _thread = import_module('_thread')
 threading = import_module('threading')

Lib/test/test_tools/__init__.py

@@ -3,7 +3,6 @@ import os
 import unittest
 import importlib
 from test import support
-from fnmatch import fnmatch
 
 basepath = os.path.dirname(                 # <src/install dir>
                 os.path.dirname(                # Lib