Explicitly free packet on PF_DROP, otherwise a "quick" rule with
"route-to" may still forward it.

PR:		177808
Submitted by:	Kajetan Staszkiewicz <kajetan.staszkiewicz innogames.de>
Sponsored by:	InnoGames GmbH


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270928 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f