polkitunixprocess: Deprecate racy APIs

It's only safe for processes to be created with their owning uid,
(without kernel support, which we don't have).  Anything else is
subject to clients exec()ing setuid binaries after the fact.
pkcheck: Support --process=pid,start-time,uid syntax too

The uid is a new addition; this allows callers such as libvirt to
close a race condition in reading the uid of the process talking to
them.  They can read it via getsockopt(SO_PEERCRED) or equivalent,
rather than having pkcheck look at /proc later after the fact.

Programs which invoke pkcheck but need to know beforehand (i.e.  at
compile time) whether or not it supports passing the uid can
use:

pkcheck_supports_uid=$($PKG_CONFIG --variable pkcheck_supports_uid polkit-gobject-1)
test x$pkcheck_supports_uid = xyes
Update NEWS for release

Signed-off-by: Miloslav Trmač <mitr@redhat.com>
Post-release version bump to 0.113