bpo-40280: Block more non-working syscalls in Emscripten (GH-31757)

- getgroups always fails.
- geteuid and getegid always return 0 (root), which confuse tarfile and
  tests.
- hardlinks (link, linkat) always fails.
- non-encodable file names are not supported by NODERAWFS layer.
- mark more tests with dependency on subprocess and multiprocessing.
  Mocking does not work if the module fails to import.

1 files changed, 2 insertions, 0 deletions

diff --git a/Lib/distutils/tests/test_file_util.py b/Lib/distutils/tests/test_file_util.py
index a614219..551151b 100644
--- a/Lib/distutils/tests/test_file_util.py
+++ b/Lib/distutils/tests/test_file_util.py
@@ -79,6 +79,7 @@ class FileUtilTestCase(support.TempdirManager, unittest.TestCase):
                 fobj.write('spam eggs')
             move_file(self.source, self.target, verbose=0)
 
+    @unittest.skipUnless(hasattr(os, 'link'), 'requires os.link')
     def test_copy_file_hard_link(self):
         with open(self.source, 'w') as f:
             f.write('some content')
@@ -99,6 +100,7 @@ class FileUtilTestCase(support.TempdirManager, unittest.TestCase):
         with open(self.source, 'r') as f:
             self.assertEqual(f.read(), 'some content')
 
+    @unittest.skipUnless(hasattr(os, 'link'), 'requires os.link')
     def test_copy_file_hard_link_failure(self):
         # If hard linking fails, copy_file() falls back on copying file
         # (some special filesystems don't support hard linking even under