this object has a ref from being created, and its lifetime is expected to
be a single frame, so remove that initial ref when we expect to stop
using it
Closes: #2648
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4768>
 
    util_copy_framebuffer_state(&ctx->fb_state, state);
 
-   struct zink_framebuffer *fb = create_framebuffer(ctx);
+   struct zink_framebuffer *fb = ctx->framebuffer;
+   /* explicitly unref previous fb to ensure it gets destroyed */
+   if (fb)
+      zink_framebuffer_reference(screen, &fb, NULL);
+   fb = create_framebuffer(ctx);
    zink_framebuffer_reference(screen, &ctx->framebuffer, fb);
    zink_render_pass_reference(screen, &ctx->gfx_pipeline_state.render_pass, fb->rp);