Exclude closures defined in formula_fn from analysis and borrowck

[coord-e]

follow-up of #64
extracted from #57

formula_fn with existential quantification would contain closures. They're syntactically contained in the formula_fn f, but are expanded to top-level function in MIR and are processed as usual by Thrust and rustc, which is undesired. This PR makes it skip analysis and borrowck if the function is a closure defined within formula_fn.

This PR also deal with closures defined within #[thrust::ignored] or some other functions that are skipped by Thrust

[Copilot]

Pull request overview

Adjusts Thrust’s analysis pipeline to ignore MIR bodies generated for closures that originate inside #[thrust::formula_fn] functions, avoiding unintended analysis/borrowck work on compiler-generated closure items.

Changes:

• Skip local refinement/analysis for MIR items whose typeck_root_def_id is already marked as skipped.
• Skip mir_borrowck not only for #[thrust::formula_fn] items themselves, but also for their generated closure bodies (via typeck_root_def_id).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/analyze/crate_.rs	Adds a root-def-id based early return to skip analysis of closures/synthetic bodies under already-skipped defs.
src/analyze.rs	Extends borrowck skipping to closures whose root def is annotated #[thrust::formula_fn].

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