Adjust to .result -> .optresult change for OptimizationState

[serenity4]

Fixes #633 for version 2.17.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

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Files with missing lines	Patch %	Lines
src/interpreter.jl	0.00%	8 Missing ⚠️

Additional details and impacted files

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##             2.17    #634   +/-   ##
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[serenity4]

Besides the renaming, an additional fix was needed: we relied on the optimizer setting the .inlining_cost field of the source CodeInfo, while with JuliaLang/julia#57979 this operation is more explicit and set only when required during finish!. Because we create the OptimizedSource before finish!, and we rely on its .isinlineable field to be set for src_inlining_policy, it seems we must compute the inlining cost ourselves before hand.

I'll look into whether we really need to hold this information in OptimizedSource, don't merge this just yet.
EDIT: can be merged now and revisited later.