net: Introduce announce timer

The 'announce timer' will be used by migration, and explicit
requests for qemu to perform network announces.

Based on the work by Germano Veit Michel <germano@redhat.com>
 and Vlad Yasevich <vyasevic@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
diff --git a/migration/migration.c b/migration/migration.c
index 37e06b7..a9c4c6f 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -45,6 +45,7 @@
 #include "migration/colo.h"
 #include "hw/boards.h"
 #include "monitor/monitor.h"
+#include "net/announce.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */