Add struct cpumask stub used by virtio_config.h.

Created using Cursor CLI.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 tools/virtio/linux/cpumask.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/virtio/linux/cpumask.h b/tools/virtio/linux/cpumask.h
index 307da69d6b26..38ffc00e149d 100644
--- a/tools/virtio/linux/cpumask.h
+++ b/tools/virtio/linux/cpumask.h
@@ -4,4 +4,8 @@
 
 #include <linux/kernel.h>
 
+struct cpumask {
+	unsigned long bits[1];
+};
+
 #endif /* _LINUX_CPUMASK_H */
-- 
MST