Remove $FreeBSD$: one-line nroff pattern

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

patch(1): Fix a few mandoc related issues

- no blank before trailing delimiter

MFC after: 1 week

patch(1): give /dev/null patches special treatment

We have a bad habit of duplicating contents of files that are sourced from
/dev/null and applied more than once... take the more sane (in most ways)
GNU route and complain if the file exists and offer reversal options.

This still falls short a little bit as selecting "don't reverse, apply
anyway" will still give you duplicated file contents. There's probably other
issues as well, but awareness is the first step to happiness.

MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D21535

Remove automatic checkout feature.

Obtained from: DragonFly via OpenBSD
Relnotes: yes
MFC: never

patch(1): Add -Vnone option to disable backup files

Differential Revision: https://reviews.freebsd.org/D3146
Reviewed by: pfg
Approved by: markj (mentor)
MFC after: 1 week
Relnotes: yes
Sponsored by: EMC / Isilon Storage Division

patch: add dry-run alias for compatibility with other implementations.

Other implementations of patch(1), including GNU patch and "svn patch"
have a --dry-run option which does the same as our -C or --check
option.

Add a new alias to make our implementation more compatible.

MFC after: 1 week

Avoid zeroing during allocation.

This change reverts a change from OpenBSD which made use of
calloc, and therefore wasted time initializing arrays that
will later be realloc'ed. Consistently use FreeBSD's
reallocf().

While here also merge the changes from OpenBSD's manpage
patch.1 Rev 1.27:
"patch was moved from user portability (UP) to base in issue 7
and is no longer optional"

MFC after: 1 week

Remove contractions.

- Refresh code with latest OpenBSD revisions.
- Remove $DragonFly$ tags as they are using git nowadays and VCS tags will
not help merging.
- Other changes to Copyright headers to make them consistent with other
source code, we intend to fork from this point.

Reviewed by: pfg

- Add a BSD-licensed patch, ported by Pedro F. Giffuni (pfg) from
DragonflyBSD and install it as bsdpatch. WITH_BSD_PATCH makes it
default and installs GNU patch as gnupatch.

Submitted by: pfg
Obtained from: The DragonflyBSD Project

Import of a BSD-licensed version of `patch', which will eventually
replace the version we currently have in src/gnu/usr.bin/patch/.
Among other things, this version includes a --posix option for strict
POSIX conformance.

This version is the current source from OpenBSD as of today. It is
their 3.5-release, plus a few updates to patch.c and pch.c that they
made about three weeks ago.

kill the undead

Finish importing Lite2's src/usr.bin, except for ex, diff, grep, mail,
pascal and vmstat.sparc. All changed files on the vendor branch should
already have been imported.

This commit was generated by cvs2svn to compensate for changes in r13122,
which included commits to RCS files with non-trunk default branches.

BSD 4.4 Lite Usr.bin Sources