gh-109593: Fix reentrancy issue in multiprocessing resource_tracker (#109629)

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Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Lib/threading.py

@@ -245,6 +245,13 @@ class _RLock:
     def _is_owned(self):
         return self._owner == get_ident()
 
+    # Internal method used for reentrancy checks
+
+    def _recursion_count(self):
+        if self._owner != get_ident():
+            return 0
+        return self._count
+
 _PyRLock = _RLock