files intentionally left after distclean

[Karl Berry]

make distcheck Automake 1.5 complains if any files at all are left in
=build after make distclean.  As it happens, in texinfo I distribute
several files (the .info files, the man pages, a few generated sources)
that also get built, because there's no harm in it, and it reduces
frustration in case of portability problems, i.e., if the building
fails.

So, I suggest making this only complain about files in =build that are
not in the original source directory against =build.  As it is, I had to
hack distdir.am to remove the check to make my distribution.

Also, it would be nice to list the problematic files.

Thanks,
karl