This fixes issue [#105100](https://projects.blender.org/blender/blender/issues/105100) where multi-pass renders can be incorrect due to kernels using stale specialisation constants (e.g. when rendering Pokedstudio).
This patch adds a new group of md5 hashes (`global_defines_md5`) to track whether the injected block of #defines is stale and regenerate the source string as appropriate. It also renames the existing group of md5 hashes from `source_md5` to `kernels_md5` to clarify that these refer to a specific kernel set rather than just the source (which might build an arbitrarily large number of kernel sets).
Pull Request #105103
482fb791ce