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
Make SOCK_RAW sockets to be truly raw, not modifying received and sent
packets at all. Swapping byte order on SOCK_RAW was actually a bug, an
artifact from the BSD network stack, that used to convert a packet to
native byte order once it is received by kernel.

Other operating systems didn't follow this, and later other BSD
descendants fixed this, leaving us alone with the bug. Now it is
clear that we should fix the bug.

In collaboration with:	Olivier Cochard-Labbé <olivier cochard.me>
See also:		https://wiki.freebsd.org/SOCK_RAW
Sponsored by:		Nginx, Inc.
Do not generate unwind info in asm functions if _STANDALONE is defined.
The .fnend op causes the assembler to emit RELOC references to unwind
support functions that don't exist in libstand.