Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

libsysdecode: Include required headers in sysdecode.h

Make sysdecode.h self-contained rather than forcing all consumers to
include dependencies. No functional change intended.

Reviewed by: pauamma_gundo.com, jhb, emaste
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34899

Drop "All rights reserved" from my copyright statements.

Reviewed by: rgrimes
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D19485

Improve the decoding of the third argument of the socket() call.

Decoding of the third argument depends on the first one. For doing this,
add a corresponding function to libsysdecode.

Thanks to jhb@ for suggesting this.