gh-106320: Remove private _PyLong converter functions (#108499)

Move these private functions to the internal C API (pycore_long.h):

* _PyLong_UnsignedInt_Converter()
* _PyLong_UnsignedLongLong_Converter()
* _PyLong_UnsignedLong_Converter()
* _PyLong_UnsignedShort_Converter()

Argument Clinic now emits #include "pycore_long.h" when these
functions are used.

Author: vstinner

Include/cpython/longobject.h

@@ -2,10 +2,6 @@
 #  error "this header file must not be included directly"
 #endif
 
-PyAPI_FUNC(int) _PyLong_UnsignedShort_Converter(PyObject *, void *);
-PyAPI_FUNC(int) _PyLong_UnsignedInt_Converter(PyObject *, void *);
-PyAPI_FUNC(int) _PyLong_UnsignedLong_Converter(PyObject *, void *);
-PyAPI_FUNC(int) _PyLong_UnsignedLongLong_Converter(PyObject *, void *);
 PyAPI_FUNC(int) _PyLong_Size_t_Converter(PyObject *, void *);
 
 PyAPI_FUNC(PyObject*) PyLong_FromUnicodeObject(PyObject *u, int base);

Include/internal/pycore_long.h

@@ -186,6 +186,13 @@ extern char* _PyLong_FormatBytesWriter(
     int base,
     int alternate);
 
+// Argument converters used by Argument Clinic
+PyAPI_FUNC(int) _PyLong_UnsignedShort_Converter(PyObject *, void *);
+PyAPI_FUNC(int) _PyLong_UnsignedInt_Converter(PyObject *, void *);
+PyAPI_FUNC(int) _PyLong_UnsignedLong_Converter(PyObject *, void *);
+PyAPI_FUNC(int) _PyLong_UnsignedLongLong_Converter(PyObject *, void *);
+
+
 /* Long value tag bits:
  * 0-1: Sign bits value = (1-sign), ie. negative=2, positive=0, zero=1.
  * 2: Reserved for immortality bit