Remove outdated Python pre-3.9 code

TMP

Author: DimitriPapadopoulos

testing/cffi0/backend_tests.py

@@ -2,7 +2,6 @@
 import platform
 import sys, ctypes, ctypes.util
 from cffi import FFI, CDefError, FFIError, VerificationMissing
-from testing.support import *
 
 SIZE_OF_INT   = ctypes.sizeof(ctypes.c_int)
 SIZE_OF_LONG  = ctypes.sizeof(ctypes.c_long)

testing/cffi0/test_verify.py

@@ -2,7 +2,6 @@
 import pytest
 import sys, os, math, weakref
 from cffi import FFI, VerificationError, VerificationMissing, model, FFIError
-from testing.support import *
 from testing.support import extra_compile_args, is_musl
 
 # eliminate warning noise from common test modules that are repeatedly re-imported