sockstat: fix the -j option with piped output after libxo integration

The legacy code handling -j in display() was causing xo_finish() to be
skipped. It has also been causing a memory leak since 0726c6574f8
(sockstat: Add automatic column sizing and remove -w option)

Fixes: 7b35b4d1963 (sockstat: add libxo support)
MFC after: 1 week
Reported by: glebius
Reviewed by: glebius
Sponsored by: ConnectWise
Pull Request: https://github.com/freebsd/freebsd-src/pull/1842