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

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

Doh! r188813 modified an auto-generated file. Fix it for real:
o grammar fix
o remove mention of libkse

Submitted by: Niclas Zeising <niclas.zeising@gmail.com>

Mdoc fix.

Submitted by: ru
Approved by: re(implicit)

Repo copy libpthreads to libkse.
This introduces the WITHOUT_LIBKSE nob,
and changes WITHOUT_LIBPTHREADS to mean with neither threading libs.
Approved by: re(kensmith)

Prepare to autogenerate the src.conf(5) manpage.