The Simple Stare glare code writes and reads from the same image in the
same invocation, so we need to insert a fence after the writes.
This is not very efficient, and we can probably use a single fence
between the causal and anti-causal passes. But this can be implemented
later as an optimization.
Pull Request: https://projects.blender.org/blender/blender/pulls/133968
2d1e64d32d