vulkan/cmd_queue: handle beta extensions.

Since this was moved to vulkan_core.h, we have to add the beta header
ourselves when required.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21806>

src/vulkan/util/vk_cmd_queue_gen.py

@@ -69,6 +69,9 @@ TEMPLATE_H = Template(COPYRIGHT + """\
 
 #define VK_PROTOTYPES
 #include <vulkan/vulkan_core.h>
+#ifdef VK_ENABLE_BETA_EXTENSIONS
+#include <vulkan/vulkan_beta.h>
+#endif
 
 #ifdef __cplusplus
 extern "C" {