- 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

style(9): return type on separate line from function name.

Remove unneeded $FreeBSD$ tags.

- Remove the old insque() and remque() functions and their manual
page from the compatibility library.
- Add new implementations of insque() and remque() which conform to
IEEE Std 1003.1-2001 to libc. Add a new manual page for them and
connect them to the build.
- Add the prototypes of insque() and remque() to the search.h
header.