Add MigrationParams structure

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
diff --git a/qemu-common.h b/qemu-common.h
index 9d9e603..c8c6b2a 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -17,6 +17,7 @@
 
 struct Monitor;
 typedef struct Monitor Monitor;
+typedef struct MigrationParams MigrationParams;
 
 /* we put basic includes here to avoid repeating them in device drivers */
 #include <stdlib.h>