Summary:
Previously on large types OIL would have problems with corrupting the `std::stack<exporter::inst::Inst>` that is passed to the processors. This change hides the implementation of the stack from the processors by wrapping the call to emplace in a `std::function` written by the non-generated code, which solves the test case I've seen for this crashing. It also allows us to easily change the stack implementation in future - I plan to change it to a `std::stack<T, std::vector<T>>` in a follow up.
Reviewed By: tyroguru
Differential Revision: D49273116
