tools: gpgconf: Killing order is children-first.

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

--

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>

tools/gpgconf-comp.c

@@ -1343,7 +1343,7 @@ gc_component_kill (int component)
     }
 
   /* Do the restart for the selected backends.  */
-  for (backend = 0; backend < GC_BACKEND_NR; backend++)
+  for (backend = GC_BACKEND_NR-1; backend; backend--)
     {
       if (runtime[backend] && gc_backend[backend].runtime_change)
         (*gc_backend[backend].runtime_change) (1);