pysss: Suppress warning Wincompatible-pointer-types
    
    struct PyMethodDef has PyCFunction in definition as ml_meth
    but we are using PyCFunctionWithKeywords
    
    src/python/pysss.c:910:40: warning: initialization of
        ‘PyObject * (*)(PyObject *, PyObject *)’
        {aka ‘struct _object * (*)(struct _object *, struct _object *)’}
        from incompatible pointer type
        ‘PyObject * (*)(PyObject *, PyObject *, PyObject *)’
        {aka ‘struct _object * (*)(struct _object *, struct _object *,
                                   struct _object *)’}
        [-Wincompatible-pointer-types]
         { sss_py_const_p(char, "useradd"), (PyCFunction) py_sss_useradd,
                                            ^
    src/python/pysss.c:910:40: note: (near initialization for
        ‘sss_local_methods[0].ml_meth’)
    
    Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
    (cherry picked from commit 187f68360de1e452afce699706a4253f3fc71a1f)