gcc 3.2's cpp breaks configure scripts

[Joe Buck]

> > The Right Thing to do is not to add -I/usr/include because that can cause
> > subtle breakage as well.
> 
> Or maybe the right thing is to fix autoconf so that it doesn't think a  
> warning is a fatal error.

The problem is that there are very large numbers of GNU and other freeware
packages out there with this defect in their autoconf files.  When we
release 3.2, people are going to have a bear of a time building
distributions.  It will be seen as a gcc problem, even if a good argument
can be made that it is an autoconf problem.