- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Improve bsdpatch usability:

- Ask only once for "Apply anyway". [1]
- Tell user what file have failed patch rather than just how
many hunks failed.

Reported by: jmg via pfg [1]
Tested by: pfg [1]
Approved by: re (gjb)

patch: style fix

Submitted by: gogolok

Revert r250972 to fix build.

The error handling for writes to the target file could lead to the final
fclose() being skipped. Fix this by using boolean "&" and "|" instead of
short-cut operators "&&" and "||".
While here, increment the last part of the version string. The reason is
the fixed output file selection logic in pch.c, which was committed as
r250943, yesterday.

Reviewed by: pfg

- 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