bpo-42431: Fix outdated bytes comments (GH-23458)
Also move definitions of internal macros F_LJUST etc to private header.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f6473c0..4093555 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -42,6 +42,7 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_bytes_methods.h" // _Py_bytes_lower()
+#include "pycore_format.h" // F_LJUST
#include "pycore_initconfig.h" // _PyStatus_OK()
#include "pycore_interp.h" // PyInterpreterState.fs_codec
#include "pycore_object.h" // _PyObject_GC_TRACK()