gh-111178: Skip tests which require deep stack if UBsan (#131669)

If Python is built with Undefined Behavior sanitizer, skip
test_repr_deep() of test_userdict and test_lru_recursion() of
test_functools.

Author: vstinner

Diff for: Lib/test/mapping_tests.py

@@ -624,6 +624,7 @@ def __repr__(self):
 
     @support.skip_wasi_stack_overflow()
     @support.skip_emscripten_stack_overflow()
+    @support.skip_if_sanitizer("requires deep stack", ub=True)
     def test_repr_deep(self):
         d = self._empty_mapping()
         for i in range(support.exceeds_recursion_limit()):

Diff for: Lib/test/test_functools.py

@@ -2078,7 +2078,7 @@ def orig(a, /, b, c=True): ...
 
     @support.skip_on_s390x
     @unittest.skipIf(support.is_wasi, "WASI has limited C stack")
-    @support.skip_if_sanitizer("requires deep stack", thread=True)
+    @support.skip_if_sanitizer("requires deep stack", ub=True, thread=True)
     @support.skip_emscripten_stack_overflow()
     def test_lru_recursion(self):