migration: move include files to include/migration/

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/migration-exec.c b/migration-exec.c
index 3e55b77..784486d 100644
--- a/migration-exec.c
+++ b/migration-exec.c
@@ -17,7 +17,7 @@
 
 #include "qemu-common.h"
 #include "qemu_socket.h"
-#include "migration.h"
+#include "migration/migration.h"
 #include "buffered_file.h"
 #include "block/block.h"
 #include <sys/types.h>