Fix Makefile for FDL version fix

[Paul Eggert]

On 02/24/2012 01:58 PM, Roland McGrath wrote:
> For some reason I can't recall, whoever it was
> (Paul Eggert, I think, but I'm not sure) seemed to think it was intractable
> to get the canonical texinfo.tex to drop the trailing whitespace.

I just now emailed a request to bug-texinfo@gnu.org to elide the
trailing white space; it's Message-ID <4F480C8B.2070001@cs.ucla.edu>.

I don't recall the earlier discussion,
but then again, there's a lot that I don't recall....