raising minimum Texinfo requirement in src tree

[Ben Elliston]

I've just committed a patch that raises the minimum requirement on
Texinfo from version 4.2 (released in April 2002) to Texinfo 4.4
(released in January 2003).  DJ has advised me to consult with these
projects about the change.  Does anyone have any objections?  If so, I
will back it out and we can discuss.

FWIW, I have been using Texinfo 4.8 on my Debian GNU/Linux system.  I
think this is a pretty conservative change that is needed to support
some fairly modern Texinfo constructs in the binutils documentation.

Thanks, Ben