pythongh-109615: Look for 'Modules' as landmark for test_copy_python_src_ignore (pythonGH-110108)

(cherry picked from commit 20bc5f7)

Author: zooba

Lib/test/test_support.py

@@ -777,7 +777,9 @@ def test_copy_python_src_ignore(self):
         if not os.path.exists(src_dir):
             self.skipTest(f"cannot access Python source code directory:"
                           f" {src_dir!r}")
-        landmark = os.path.join(src_dir, 'Lib', 'os.py')
+        # Check that the landmark copy_python_src_ignore() expects is available
+        # (Previously we looked for 'Lib\os.py', which is always present on Windows.)
+        landmark = os.path.join(src_dir, 'Modules')
         if not os.path.exists(landmark):
             self.skipTest(f"cannot access Python source code directory:"
                           f" {landmark!r} landmark is missing")