os/xdmcp: Honour -once when session is dead

Terminate a dead session when -once was passed. Don't restart it.

Signed-off-by: Daniel Martin <consume.noise@gmail.com>
Reviewed-by: Walter Harms <wharms@bfs.de>
(cherry picked from commit 918afeecbc)

os/xdmcp.c

@@ -797,7 +797,7 @@ XdmcpDeadSession(const char *reason)
     ErrorF("XDM: %s, declaring session dead\n", reason);
     state = XDM_INIT_STATE;
     isItTimeToYield = TRUE;
-    dispatchException |= DE_RESET;
+    dispatchException |= (OneSession ? DE_TERMINATE : DE_RESET);
     TimerCancel(xdmcp_timer);
     timeOutRtx = 0;
     send_packet();