Add -no-virtio-balloon command-line option

This new option may be used to disable the virtio-balloon device.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/vl.c b/vl.c
index 40fc3a4..3d213f3 100644
--- a/vl.c
+++ b/vl.c
@@ -244,6 +244,7 @@
 const char *vnc_display;
 int acpi_enabled = 1;
 int no_hpet = 0;
+int no_virtio_balloon = 0;
 int fd_bootchk = 1;
 int no_reboot = 0;
 int no_shutdown = 0;
@@ -5551,6 +5552,9 @@
             case QEMU_OPTION_no_hpet:
                 no_hpet = 1;
                 break;
+            case QEMU_OPTION_no_virtio_balloon:
+                no_virtio_balloon = 1;
+                break;
 #endif
             case QEMU_OPTION_no_reboot:
                 no_reboot = 1;