Fix termination by signal with -no-shutdown

On signals such as SIGTERM qemu should exit instead of just stopping the VM
even with -no-shutdown.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

vl.c

diff --git a/vl.c b/vl.c
index b773d2f..0c2fc3f 100644
--- a/vl.c
+++ b/vl.c
@@ -1296,6 +1296,7 @@
 {
     shutdown_signal = signal;
     shutdown_pid = pid;
+    no_shutdown = 0;
     qemu_system_shutdown_request();
 }