Add wasm-opt-for-rust-maintenance-8.md

[brson]

Milestone Delivery Checklist

• The milestone-delivery-template.md has been copied and updated.
• The invoice form 📝 has been filled out for this milestone.
• This pull request is being made by the same account as the accepted application.
• I have disclosed any and all sources of reused code in the submitted repositories and have done my due diligence to meet its license requirements.
• In case of acceptance, the payment will be transferred to the BTC/ETH/fiat account provided in the application.
• The delivery is according to the Guidelines for Milestone Deliverables.

Link to the application pull request: w3f/Grants-Program#1305

Another upgrade to binaryen this month.

We received an issue about the lack of build caching for C++ code in this project causing long rebuilds. This one one of the noted compromises in the original design of this project. I left some comments on that issue about how the problem could resolved.

[semuelle]

Thanks for the delivery, @brson. Your milestone is hereby accepted. Evaluation notes here.

I have forwarded your invoice for processing.