bpo-37685: Use singletons ALWAYS_EQ and NEVER_EQ in more tests. (GH-15167)

diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 1cd4ea2..6c9f529 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -25,7 +25,7 @@
     ThreadPoolExecutor = None
 
 from test.support import run_unittest, TESTFN, DirsOnSysPath, cpython_only
-from test.support import MISSING_C_DOCSTRINGS, cpython_only
+from test.support import MISSING_C_DOCSTRINGS, ALWAYS_EQ
 from test.support.script_helper import assert_python_ok, assert_python_failure
 from test import inspect_fodder as mod
 from test import inspect_fodder2 as mod2
@@ -118,10 +118,6 @@
     yield
     return 'spam'
 
-class EqualsToAll:
-    def __eq__(self, other):
-        return True
-
 class TestPredicates(IsTestBase):
 
     def test_excluding_predicates(self):
@@ -2978,8 +2974,8 @@
         def foo(a, *, b:int) -> float: pass
         self.assertFalse(inspect.signature(foo) == 42)
         self.assertTrue(inspect.signature(foo) != 42)
-        self.assertTrue(inspect.signature(foo) == EqualsToAll())
-        self.assertFalse(inspect.signature(foo) != EqualsToAll())
+        self.assertTrue(inspect.signature(foo) == ALWAYS_EQ)
+        self.assertFalse(inspect.signature(foo) != ALWAYS_EQ)
 
         def bar(a, *, b:int) -> float: pass
         self.assertTrue(inspect.signature(foo) == inspect.signature(bar))
@@ -3246,8 +3242,8 @@
         self.assertFalse(p != p)
         self.assertFalse(p == 42)
         self.assertTrue(p != 42)
-        self.assertTrue(p == EqualsToAll())
-        self.assertFalse(p != EqualsToAll())
+        self.assertTrue(p == ALWAYS_EQ)
+        self.assertFalse(p != ALWAYS_EQ)
 
         self.assertTrue(p == P('foo', default=42,
                                kind=inspect.Parameter.KEYWORD_ONLY))
@@ -3584,8 +3580,8 @@
         ba = inspect.signature(foo).bind(1)
         self.assertTrue(ba == ba)
         self.assertFalse(ba != ba)
-        self.assertTrue(ba == EqualsToAll())
-        self.assertFalse(ba != EqualsToAll())
+        self.assertTrue(ba == ALWAYS_EQ)
+        self.assertFalse(ba != ALWAYS_EQ)
 
         ba2 = inspect.signature(foo).bind(1)
         self.assertTrue(ba == ba2)