[3.11] gh-108851: Fix tomllib recursion tests (#108853) (#109013)

gh-108851: Fix tomllib recursion tests (#108853)

* Add get_recursion_available() and get_recursion_depth() functions
  to the test.support module.
* Change infinite_recursion() default max_depth from 75 to 100.
* Fix test_tomllib recursion tests for WASI buildbots: reduce the
  recursion limit and compute the maximum nested array/dict depending
  on the current available recursion limit.
* test.pythoninfo logs sys.getrecursionlimit().
* Enhance test_sys tests on sys.getrecursionlimit()
  and sys.setrecursionlimit().

Backport notes:

* Set support.infinite_recursion() minimum to 4 frames.
* test_support.test_get_recursion_depth() uses limit-2, apparently
  f-string counts for 2 frames in Python 3.11.
* test_sys.test_setrecursionlimit_to_depth() tests depth+2 instead of
  depth+1.

(cherry picked from commit 8ff1142578)

Lib/test/test_tomllib/test_misc.py

@@ -9,6 +9,7 @@
 import sys
 import tempfile
 import unittest
+from test import support
 
 from . import tomllib
 
@@ -92,13 +93,23 @@ def test_deepcopy(self):
         self.assertEqual(obj_copy, expected_obj)
 
     def test_inline_array_recursion_limit(self):
-        # 465 with default recursion limit
-        nest_count = int(sys.getrecursionlimit() * 0.465)
-        recursive_array_toml = "arr = " + nest_count * "[" + nest_count * "]"
-        tomllib.loads(recursive_array_toml)
+        with support.infinite_recursion(max_depth=100):
+            available = support.get_recursion_available()
+            nest_count = (available // 2) - 2
+            # Add details if the test fails
+            with self.subTest(limit=sys.getrecursionlimit(),
+                              available=available,
+                              nest_count=nest_count):
+                recursive_array_toml = "arr = " + nest_count * "[" + nest_count * "]"
+                tomllib.loads(recursive_array_toml)
 
     def test_inline_table_recursion_limit(self):
-        # 310 with default recursion limit
-        nest_count = int(sys.getrecursionlimit() * 0.31)
-        recursive_table_toml = nest_count * "key = {" + nest_count * "}"
-        tomllib.loads(recursive_table_toml)
+        with support.infinite_recursion(max_depth=100):
+            available = support.get_recursion_available()
+            nest_count = (available // 3) - 1
+            # Add details if the test fails
+            with self.subTest(limit=sys.getrecursionlimit(),
+                              available=available,
+                              nest_count=nest_count):
+                recursive_table_toml = nest_count * "key = {" + nest_count * "}"
+                tomllib.loads(recursive_table_toml)