bug#16292: 24.3.50; info docs now contain single straight quotes instead of `'

[Juri Linkov]

>> Thanks.  I guess that's as good as it's going to get.  I was hoping
>> for a file/buffer local variable or something.  This is the kind of
>> hoop-jumping I was talking about, but I do appreciate your having
>> coded it up.
>>
>> This would need to be consulted each time an Info node is fontified.
>> Yes, the search can be done instead just whenever the Info file is
>> changed, and then saved for consultation upon node fontifying for
>> the same file.  (Still, I would hope for something simpler.)
>
> I still think that such a local variable would be useful for Emacs,

What would be useful is a variable to hold the makeinfo version
extracted from the visited Info manual.  Such variable could be used
to simplify feature checks like `Info-file-supports-index-cookies'.