test_gdb: skip test_threads when running without GIL

Author: colesbury

Lib/test/test_gdb.py

@@ -828,6 +828,7 @@ def test_bt_full(self):
 
     @unittest.skipIf(python_is_optimized(),
                      "Python was compiled with optimizations")
+    @unittest.skipIf(sys.flags.nogil, "Python is running without the GIL")
     def test_threads(self):
         'Verify that "py-bt" indicates threads that are waiting for the GIL'
         cmd = '''