gh-90473: WASI: skip gethostname tests (GH-93092)

- WASI's ``gethostname()`` is a stub that always fails with OSError
  ``ENOTSUP``
- skip mailcap ``test`` if subprocess is not available
- WASI process_time clock does not work.

Lib/test/test_time.py

@@ -489,6 +489,9 @@ class TimeTestCase(unittest.TestCase):
     def test_perf_counter(self):
         time.perf_counter()
 
+    @unittest.skipIf(
+        support.is_wasi, "process_time not available on WASI"
+    )
     def test_process_time(self):
         # process_time() should not include time spend during a sleep
         start = time.process_time()