- 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

Remove __restrict keywords from array arguments to make GCC's -std=c99 work.

When GCC is invoked with -std=c99, the following errors are displayed when
including <spawn.h>:

/usr/include/spawn.h:69: error: static or type qualifiers in abstract declarator
/usr/include/spawn.h:69: error: static or type qualifiers in abstract declarator
/usr/include/spawn.h:72: error: static or type qualifiers in abstract declarator
/usr/include/spawn.h:72: error: static or type qualifiers in abstract declarator

We'd better remove the __restrict keywords here. The same is also done
in <regex.h>.

Submitted by: Andrzej Tobola <ato iem pw edu pl>
Reviewed by: davidxu
Approved by: philip (mentor, implicit)

Change my email address to the one from the FreeBSD project.

Approved by: philip (mentor, implicit), davidxu

Add POSIX routines called posix_spawn() and posix_spawnp(), which
can be used as replacements for exec/fork in a lot of cases. This
change also added execvpe() which allows environment variable
PATH to be used for searching executable file, it is used for
implementing posix_spawnp().

PR: standards/122051