pythongh-119336: Restore _PyLong_NumBits

This is used in pywin32, and the function being moved to internal headers
broke with 3.13. Restore it for now to eventually be considered for being
made a public symbol.

See also pythongh-112026 (previous restoration) and pythongh-111481 (public replacements)

Include/cpython/longobject.h

@@ -60,6 +60,15 @@ PyAPI_FUNC(Py_ssize_t) PyUnstable_Long_CompactValue(const PyLongObject* op);
 // There are no error cases.
 PyAPI_FUNC(int) _PyLong_Sign(PyObject *v);
 
+/* _PyLong_NumBits. Return the number of bits needed to represent the
+ absolute value of a long. For example, this returns 1 for 1 and -1, 2
+ for 2 and -2, and 2 for 3 and -3. It returns 0 for 0.
+ v must not be NULL, and must be a normalized long.
+ (size_t)-1 is returned and OverflowError set if the true result doesn't
+ fit in a size_t.
+*/
+PyAPI_FUNC(size_t) _PyLong_NumBits(PyObject *v);
+
 /* _PyLong_FromByteArray: View the n unsigned bytes as a binary integer in
  base 256, and return a Python int with the same numeric value.
  If n is 0, the integer is 0. Else:

Include/internal/pycore_long.h

@@ -47,17 +47,6 @@ extern "C" {
 # error "_PY_LONG_DEFAULT_MAX_STR_DIGITS smaller than threshold."
 #endif
 
-// _PyLong_NumBits. Return the number of bits needed to represent the
-// absolute value of a long. For example, this returns 1 for 1 and -1, 2
-// for 2 and -2, and 2 for 3 and -3. It returns 0 for 0.
-// v must not be NULL, and must be a normalized long.
-// (size_t)-1 is returned and OverflowError set if the true result doesn't
-// fit in a size_t.
-//
-// Export for 'math' shared extension.
-PyAPI_FUNC(size_t) _PyLong_NumBits(PyObject *v);
-
-
 /* runtime lifecycle */
 
 extern PyStatus _PyLong_InitTypes(PyInterpreterState *);