protecting against rm -rf / is now POSIXLY_CORRECT

[bapt]

Summary

Per POSIX 1003.1, 2013:

if an operand resolves to the root directory, rm shall write a diagnostic
message to standard error and do nothing more with such operands.

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/rm.html

[imp]

You need to update the man page to say this is expected to comply with the 2013 version in the standards section.

I'm a little sad to see POSIXLY_CORRECT go, but I would have been sadder if we had the off-color POSIX_ME_HARDER and it was going...