package/s6-linux-utils: bump to 2.5.0.0

In 2.4.0.2, compilation under glibc 2.28 is fixed (and our local patch can
thus be removed).
While at it, bump to the latest released version 2.5.0.0.

Note: change in COPYING file is only the copyright year.

>From the NEWS file:
"""
In 2.5.0.0
----------
 - Optional nsss support.
 - s6-devd, s6-uevent-listener, s6-uevent-spawner removed.

In 2.4.0.2
----------
 - s6-logwatch rewrite.
 - Better portability with old glibc versions.
 - s6-uevent-listener and s6-uevent-spawner are marked as deprecated. (The
   mdevd package obsoletes them.)
"""

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>