tests: Make threading tests conditional upon thread support

tests/stdpy/test_threading.py

@@ -10,6 +10,7 @@ def test_threading_error():
 
 
 @pytest.mark.skipif(sys.platform == "emscripten", reason="No threading")
+@pytest.mark.skipif(not core.Thread.is_threading_supported(), reason="No threading")
 def test_threading():
     from collections import deque
 

tests/stdpy/test_threading2.py

@@ -6,6 +6,7 @@ import pytest
 
 
 @pytest.mark.skipif(sys.platform == "emscripten", reason="No threading")
+@pytest.mark.skipif(not core.Thread.is_threading_supported(), reason="No threading")
 def test_threading2():
     class BoundedQueue(threading2._Verbose):