"rm -rf /etc/motd" (run by non-root) now prints a diagnostic.

"rm -rf /etc/motd" (run by non-root) now prints a diagnostic.
* src/remove.c (remove_entry): Handle EACCES for a non-directory, too.
Karl Berry reported that a cross-partition "mv /etc/issue ~"
failed with the um,... suboptimal diagnostic,
"mv: cannot remove `/etc/issue': Not a directory".
* tests/rm/Makefile.am (TESTS): Add fail-eacces.
* tests/rm/fail-eacces: New file.
* NEWS: Mention that both mv and rm are affected.