[Bug-gnupress] Update Texinfo in GCC

[Simon Law]

Karl told me that GCC should be using the latest stable Texinfo to
generate its manual, since there have been bug fixes.

        gcc/gcc/doc/include/texinfo.tex is quite out of date.  In fact,
I don't think mainline actually has the latest one.  Jim should tell
them to update to Texinfo 4.5 [1].

Simon

[1] 
http://savannah.gnu.org/cgi-bin/viewcvs/texinfo/texinfo/doc/texinfo.tex?only_with_tag=texinfo_4_5