Rollup merge of #156235 - rajgandhi1:compiler_stack_overflow_fix, r=adwinwhite

fix: Guard SizeSkeleton::compute against stack overflow

Fixes rust-lang/rust#156137

Fix: extract the recursion into a private `compute_inner` that carries a depth counter. When depth exceeds the crate's recursion limit, return `LayoutError::Unknown` and let the existing transmute size-check produce a normal error instead of crashing.

A regression test is included in `tests/ui/transmute/`.