tools: gpgconf: Killing order is children-first.

tools: gpgconf: Killing order is children-first.

* tools/gpgconf-comp.c (gc_component_kill): Reverse the order.

--

Cherry-picked from master commit:
	7c877f942a344e7778005840ed7f3e20ace12f4a

The order matters in a corner case; On a busy machine, there was a
race condition between gpg-agent's running KILLAGENT command and its
accepting incoming request on the socket.  If a request by
gpg-connect-agent was accepted, it resulted an error by sudden
shutdown.  This change of the order can remove such a race.

Here, we know backend=0 is none.

GnuPG-bug-id: 4577
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
(cherry picked from commit 526714806da4e50c8e683b25d76460916d58ff41)

Gbp-Pq: Topic from-2.2.17
Gbp-Pq: Name tools-gpgconf-Killing-order-is-children-first.patch