Use rm -x only on FreeBSD 10 and newer. Many people still build from
older hosts, which still works, so don't break that gratuitously.

MFC After: 3 days
NANO_OBJ shouldn't end with a '/', so remove it here. This makes the
pathnames printed not have the dreaded // which makes it hard to cut
and paste into an emacs find file command...

MFC After: 3 days