Issue #3080: Import builtins using Unicode strings

 - is_builtin(), init_builtin(), load_builtin() and other builtin related
   functions use Unicode strings, instead of byte strings
 - Rename _PyImport_FixupExtensionUnicode() to _PyImport_FixupExtensionObject()
 - Rename _PyImport_FindExtensionUnicode() to _PyImport_FindExtensionObject()
diff --git a/Include/import.h b/Include/import.h
index 2d45238..710fd22 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -79,12 +79,12 @@
 PyAPI_FUNC(PyObject *)_PyImport_FindBuiltin(
     const char *name            /* UTF-8 encoded string */
     );
-PyAPI_FUNC(PyObject *)_PyImport_FindExtensionUnicode(const char *, PyObject *);
+PyAPI_FUNC(PyObject *)_PyImport_FindExtensionObject(PyObject *, PyObject *);
 PyAPI_FUNC(int)_PyImport_FixupBuiltin(
     PyObject *mod,
     char *name                  /* UTF-8 encoded string */
     );
-PyAPI_FUNC(int)_PyImport_FixupExtensionUnicode(PyObject*, char *, PyObject *);
+PyAPI_FUNC(int)_PyImport_FixupExtensionObject(PyObject*, PyObject *, PyObject *);
 
 struct _inittab {
     char *name;