pythongh-111415: restoring _PyLong_New() as public

This partially reverts python#108604.

Author: skirpichev

Include/cpython/longintrepr.h

@@ -89,6 +89,8 @@ struct _longobject {
     _PyLongValue long_value;
 };
 
+PyAPI_FUNC(PyLongObject *) _PyLong_New(Py_ssize_t);
+
 
 /* Inline some internals for speed. These should be in pycore_long.h
  * if user code didn't need them inlined. */

Include/internal/pycore_long.h

@@ -47,8 +47,6 @@ extern "C" {
 # error "_PY_LONG_DEFAULT_MAX_STR_DIGITS smaller than threshold."
 #endif
 
-extern PyLongObject* _PyLong_New(Py_ssize_t);
-
 // Return a copy of src.
 extern PyObject* _PyLong_Copy(PyLongObject *src);