bug#17830: 24.4.50; smie: inners and up-list

[Leo Liu]

I quite like the support for show-paren-mode in smie of 24.4 for
closers. But I often also want to be able to jump to the beginning of
the block with backward-up-list by key C-M-u.

However, if the block has inners such as `let ... in ... end' (sml-mode)
and point is between `in' and `end', backward-up-list always misses the
`let' opener. Some smie grammars take the `... in ...' out of the block
which makes backward-up-list work but show-paren-mode won't show `in' as
the inner matching `let' any more.

Any fix to this? Thanks.

Leo