remote: Revert removing "libvirt/libvirt.h" in remote_protocol.x

Commit 2d25fd4f removed the including of "libvirt/libvirt.h",
which breaks the build. Pushed under build-breaker rule.

src/remote/remote_protocol.x

@@ -36,6 +36,7 @@
  * 'REMOTE_'.  This makes names quite long.
  */
 
+%#include <libvirt/libvirt.h>
 %#include "internal.h"
 %#include <arpa/inet.h>