Hi Eli, Please help review the patch, thank you!

From: Lin Sun
> There is a bug that turn off semantic-mode it only restores current buffer's imenu-create-index-function but actually turning on semantic-mode had changed each buffer's variable.
> Reproduce steps:
> 1) Open two files (eg /tmp/a.c, /tmp/b.c) in two buffers;
> 2) Turn on semantic-mode, it will change the imenu-create-index-function value for each buffer;
> 3) Turn off semantic-mode, it will restore current buffer's value (eg: b.c), but another one (eg: a.c) won't restored.
>
> When turning on semantic-mode, it applies changes to each buffer,
>  1048         (dolist (b (buffer-list))
>  1049           (with-current-buffer b
>  1050             (semantic-new-buffer-fcn))))
>
> But turning off semantic does not restore the var for each buffer, only restores current buffer.
>
> This patch will fix the issue. Please help review it. Thanks.