bug#12320: bison 2.6.2 contains stale info files

[Karl Berry]

    So, Karl, Jim, and others, would you accept that gendocs.sh
    stopped generating a compressed tarball of split info files,
    but would rather ship a compressed --no-split file?

Well, I hope meeting you halfway is ok ... I just changed gendocs.sh to
default to --no-split (can be overridden with a new --info option).

However, I kept it generating a tarball even though usually it will be a
tarball of one file, because otherwise, it would be necessary to detect
when split output was being generated, etc., etc.  Didn't seem worth the
trouble.

At least once you remove the stray split files now, they shouldn't
reappear ...

k