perror(1): Reorder headers alphabetically to meet style(9) compliance
Signed-off-by: Faraz Vahedi <kfv@kfv.io>
Reviewed by: markj, oshogbo
MFC after: 1 week
Pull Request: https://github.com/freebsd/freebsd-src/pull/1492
(cherry picked from commit 82e9f8c2d19ba5d132438a764352eb3b4826fc58)