bpo-40214: Temporarily disable a ctypes test (GH-19404)

Only one particular sub-test of
ctypes.test.test_loading.test_load_dll_with_flags is disabled, which
caused failures on Azure Pipelines CI.

Lib/ctypes/test/test_loading.py

@@ -158,6 +158,9 @@ class LoaderTest(unittest.TestCase):
             # Relative path (but not just filename) should succeed
             should_pass("WinDLL('./_sqlite3.dll')")
 
+            # XXX: This test has started failing on Azure Pipelines CI.  See
+            #      bpo-40214 for more information.
+            if 0:
                 # Insecure load flags should succeed
                 should_pass("WinDLL('_sqlite3.dll', winmode=0)")