bpo-33629: Prevent coredump in test_importlib (GH-7090)

bpo-32374, bpo-33629: Use support.SuppressCrashReport() in
test_bad_traverse() of MultiPhaseExtensionModuleTests to prevent
leaking a core dump file.
(cherry picked from commit 483000e1)
Co-authored-by: Victor Stinner <vstinner@redhat.com>

Lib/test/test_importlib/extension/test_loader.py

@@ -275,10 +275,13 @@ class MultiPhaseExtensionModuleTests(abc.LoaderTests):
             (Multiphase initialization modules only)
         '''
         script = """if True:
+                from test import support
                 import importlib.util as util
                 spec = util.find_spec('_testmultiphase')
                 spec.name = '_testmultiphase_with_bad_traverse'
-                m = spec.loader.create_module(spec)"""
+
+                with support.SuppressCrashReport():
+                    m = spec.loader.create_module(spec)"""
         assert_python_failure("-c", script)