bpo-39489: Remove COUNT_ALLOCS special build (GH-18259)

Remove:

* COUNT_ALLOCS macro
* sys.getcounts() function
* SHOW_ALLOC_COUNT code in listobject.c
* SHOW_TRACK_COUNT code in tupleobject.c
* PyConfig.show_alloc_count field
* -X showalloccount command line option
* @test.support.requires_type_collecting decorator
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 62f2d54..a9d31af 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -3,8 +3,7 @@
 """
 
 import test.support
-from test.support import (verbose, import_module, cpython_only,
-                          requires_type_collecting)
+from test.support import verbose, import_module, cpython_only
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
 import random
@@ -552,7 +551,6 @@
         self.assertEqual(err, b"")
         self.assertEqual(data, "Thread-1\nTrue\nTrue\n")
 
-    @requires_type_collecting
     def test_main_thread_during_shutdown(self):
         # bpo-31516: current_thread() should still point to the main thread
         # at shutdown
@@ -1113,7 +1111,6 @@
         self.assertIn("ZeroDivisionError", err)
         self.assertNotIn("Unhandled exception", err)
 
-    @requires_type_collecting
     def test_print_exception_stderr_is_none_1(self):
         script = r"""if True:
             import sys