Improve backward compatibility of save-restriction

Improve backward compatibility of save-restriction

* src/editfns.c (save_restriction_save_1): Renamed from
'save_restrictions_save'.  Make it static.
(save_restriction_restore_1): Renamed from
'save_restriction_restore'.  Make it static.
(save_restriction_restore): New function, combining
'save_restriction_save_1' and 'narrowing_locks_save'.
(save_restriction_save): New function, combining
'save_restriction_restore_1' and 'narrowing_locks_restore'.
(Fsave_restriction): Restore the previous code.
(narrowing_locks_save, narrowing_locks_restore): Make them static.

* src/lisp.h: Remove two functions that are not externally visible
anymore.

* src/comp.c (helper_save_restriction): Restore the previous code.

* src/bytecode.c (exec_byte_code): Restore the previous code.

* lisp/emacs-lisp/bytecomp.el (byte-compile-save-restriction):
Decrement unbinding count.