building the manual fails with Texinfo 6

[Mike Miller]

Maintainers,

It's been found in Debian that Octave fails to build its Texinfo manual
with the latest GNU Texinfo version 6 [1]. I have updated to Texinfo 6
and can confirm building the default branch fails.

This is *not* related to the recent non-recursive make changes that have
broken some minor things in the doc and test directories, this applies
to both 3.8.2 and 4.0.0.

With some investigation and patches provided by Norbert Preining [2],
the following two changes are needed at a minimum to get it building
again:

 * delete (or update to latest) doc/texinfo.tex distributed with Octave
 * fix some unescaped backslashes in @qcode{} macros

Questions:

Why do we distribute our own texinfo.tex file? Was this to ensure that a
new enough version of the macros were present even if users had an
ancient automake or texinfo distribution once upon a time? A newer
up-to-date version of texinfo.tex is already injected into our build-aux
directory by gnulib and we could easily use that file instead to fix the
first problem.

Norbert also recommended deleting our distributed texmf.cnf, which only
exists to set save_size to 10000. The current texmf.cnf on my Debian
system sets save_size to 50000, does anyone remember which distros still
suffer from a default save_size that is too small to build the manual,
is this still relevant? RHEL 5 has save_size = 5000 for example, I
haven't tested whether this is too low.

I'll do some more testing and follow up when I have some concrete
changes for review or testing. I think this is worth fixing on the
stable branch so the 4.0.1 release will work with Texinfo 6.

[1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=790626
[2]: 
https://bugs.debian.org/cgi-bin/bugreport.cgi?att=1;msg=82;bug=790626;filename=octave-build-fix.debdiff

-- 
mike