renderonly: close transfer prime_fd

prime_fd is only used to transfer the scanout buffer to the GPU inside
renderonly_create_kms_dumb_buffer_for_resource. It should be closed
immediately to avoid leaking the DMA-BUF file handle.

Fixes: 848b49b288 ("gallium: add renderonly library")
CC: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>

src/gallium/auxiliary/renderonly/renderonly.c

@@ -116,6 +116,8 @@ renderonly_create_kms_dumb_buffer_for_resource(struct pipe_resource *rsc,
    scanout->prime = screen->resource_from_handle(screen, rsc,
          &handle, PIPE_HANDLE_USAGE_READ_WRITE);
 
+   close(prime_fd);
+
    if (!scanout->prime) {
       fprintf(stderr, "failed to create resource_from_handle: %s\n", strerror(errno));
       goto free_dumb;