autoconf-2.64 required?

[Daniel J Sebald]

> Autoconf 2.64 is really very new; though by the time Octave 3.4 will
> be released, it may already be widespread.
> However, in this case apparently it's just m4_ifblank and m4_ifnblank
> missing, so an easy remedy is to steal them out from autoconf 2.64 and
> define them ourselves if they're not there:
> http://hg.savannah.gnu.org/hgweb/octave/rev/691545147aca
>
> this enables use of autoconf 2.63 for me.

Wait a second...

First, shouldn't a copyright notice be given if hunks of autoconf are moved 
into Octave?

Second, for years I've occassionally (well, more than occassionally) fallen behind in 
autoconf or some other tool and the only deference I got from the list was to 
"download the latest version of autoconf".  (autoconf is not that difficult to 
keep up to date.)  Now we start adding little hunks to work around this issue?  Avoiding 
using the new macro is fine, but pulling in patches seems bad practice.

If anything, an expiration date (i.e., a note/date saying remove this a year or 
two from now) should be put on that hunk of code so that someone can take it 
out when it is extraneous.

Dan