Bug diff: no difference between 0 byte files and no files.

[J.C. Pizarro]

Hi, diff v2.8.1 and v2.8.7 ignore 0 byte files, and it's a bug.

The program diff doesn't see the difference between 0 byte file and no file.

  mkdir dir1 dir2 2> /dev/null ; cat /dev/null > dir1/empty.out ; \
  tree dir1 dir2 ; echo "Differences between dir1 and dir2 from diff:" ; \
  diff -Nduar dir1 dir2 ; rm -f dir1/empty.out ; rmdir dir1 dir2

If dir1 contains 0 byte files, and dir2 no files, the problem comes when i
patch the dir1_to_dir2.patch and in dir2 appear 0 byte files instead of no
files. The elimination of 0 byte files should have ocurred here but it didn't.

J.C. sincerely yours :)