- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r264400,r265836:

r264400:

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

r265836:

Remove last two NO_MAN= in the tree. In both of these cases, MAN= is
what is needed.

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

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

Fixed missing or broken library dependencies.

Update the sendfile regression test so that it outputs results in the
TAP format.
Add a checksum to verify that the data hasn't been corrupted between
being read from disk and being received.

Approved by: rrs (mentor)

Valid error codes for err() and errx() are 1..255.
The correct format specifier for ssize_t is %zd.

o style.Makefile(5): WARNS= -> WARNS?=.

Use WARNS and rely on rules rather than an explicit target for the
test binary.

Reported by: maxim

Add a basic regression test for sendfile() over TCP, which sends varying
lengths of headers and data and makes sure it receives about the right
number of bytes.