setaudit: Bump WARNS and fix some style bugs

• Cast sockaddrs through void to silence warnings about expected alignment.
• Fix cast style.
• Sort includes.
• Make some global variables local.
• Sort options.

No functional change intended.

Reviewed by: csjp
MFC after: 2 weeks
Sponsored by: Modirum MDPay
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D53670