Remove $FreeBSD$: one-line .c comment pattern

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

libnetbsd: Make the function declaration of efopen() match the definition

In order to crossbuild FreeBSD on Mac/Linux I also need to build libnetbsd
and FILE* is not equal to struct __sFILE on those platforms.

Reviewed By: brooks, emaste
Approved By: jhb (mentor)
Differential Revision: https://reviews.freebsd.org/D13305

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

libnetbsd: add emalloc and friends

These are error-checked versions of memory allocation routines used by
NetBSD code, and are being added to facilitate updates to makefs.

Reviewed by: ngie
Differential Revision: https://reviews.freebsd.org/D10291

Port the getaddrinfo(1) utility from NetBSD

Submitted by: Lohith Bellad <lohithbsd@gmail.com>
Reviewed by: hiren (earlier rev), ae
Obtained from: NetBSD
MFC after: 1 week
Relnotes: yes
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9365

libnetbsd: more portability fixes with stdio.h and util.h

- stdio.h needs to pull in stdio.h/util.h for fparseln, not util.h
- util.h needs to #include sys/types.h for flags_to_string, etc as
flags_to_string uses u_long, which is typedef'ed in sys/types.h on
FreeBSD

Add stdio.h #include for fparseln

fparseln on FreeBSD requires stdio.h, then libutil.h, whereas NetBSD only
requires util.h

Add libnetbsd, a thin compatibility layer intended to allow a limited
set of NetBSD software to compile as part of the FreeBSD build with
little or no modifiction. It is built as a static library and not
installed for general use. Likewise, its header files are not
installed.

Sponsored by: DARPA, AFRL