cext: make HgRevlogIndex_GetParents private again
The rust's direct-ffi code need to access this function. Now that it
`direct-ffi` is no more. We can make this function `static` again.
This change was suggested by `Yuya Nishihara`.
/*
revlog.h - efficient revlog parsing
This software may be used and distributed according to the terms of
the GNU General Public License, incorporated herein by reference.
*/
#ifndef _HG_REVLOG_H_
#define _HG_REVLOG_H_
#include <Python.h>
extern PyTypeObject HgRevlogIndex_Type;
#define HgRevlogIndex_Check(op) PyObject_TypeCheck(op, &HgRevlogIndex_Type)
#endif /* _HG_REVLOG_H_ */