Clarify a comment for test.support.Py_C_RECURSION_LIMIT to point out where a value came from but that it doesn't need to stay in sync (python#112224)

Author: brettcannon

Lib/test/support/__init__.py

@@ -2380,7 +2380,8 @@ def _get_c_recursion_limit():
         import _testcapi
         return _testcapi.Py_C_RECURSION_LIMIT
     except (ImportError, AttributeError):
-        return 1500  #  (from Include/cpython/pystate.h)
+        # Originally taken from Include/cpython/pystate.h .
+        return 1500
 
 # The default C recursion limit.
 Py_C_RECURSION_LIMIT = _get_c_recursion_limit()