virshConnect: Don't leak polkit agent

In our attempts to reconnect, we may create a polkit daemon.
However, it may happen that we would rewrite the variable that
already holds pointer to the agent.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

tools/virsh.c

@@ -168,7 +168,7 @@ virshConnect(vshControl *ctl, const char *uri, bool readonly)
         err = virGetLastError();
         if (err && err->domain == VIR_FROM_POLKIT &&
             err->code == VIR_ERR_AUTH_UNAVAILABLE) {
-            if (!(pkagent = virPolkitAgentCreate()))
+            if (!pkagent && !(pkagent = virPolkitAgentCreate()))
                 goto cleanup;
         } else if (err && err->domain == VIR_FROM_POLKIT &&
                    err->code == VIR_ERR_AUTH_FAILED) {