[port #1065] strip tiny source position tables at link time (design caveat)

[luantak]

Validity: questionable — design buy-in from mvdan still needed

mvdan is skeptical: further linker patches increase per-Go-release maintenance cost, and asked why short -tiny positions are a problem. Copilot High flagged an OOB concern with ^uint32(0) in cutab.

Do not present this as ready to merge upstream blindly.

Upstream

burrowers#1065

Commit layout

Commit 1 is Maremagnum's from burrowers#1065 (author preserved as on the upstream commit: autoprofiler <autoprofiler@local.invalid>); following commit(s) address luantak/mvdan review feedback and are authored by the Cursor/luantak port side.

• 16c6b01 autoprofiler | strip tiny source position tables at link time
• de0ff04 Cursor Agent | Address review feedback: write 0 into cutab placeholder

What this ports

• Linker patch 0005-strip-tiny-source-positions-safely.patch removing filename/line mappings while retaining stack maps / pcsp / pcinline / unwind data
• Updated tiny.txtar expectations (caller: ? 0, etc.)

Feedback applied

• OOB fix: write 0 into the runtime.cutab placeholder instead of ^uint32(0), so accidental lookups resolve to filetab[0] ("?") rather than an out-of-bounds index (per Copilot)
• Comment in the patch documents why

Testing

• go test -run 'TestScript/tiny$' . ✅ (exercises patched linker)

Remaining risks

• High for upstream merge: design disagreement + linker-patch maintenance burden. Functionally tested here on Linux, but mvdan may reject the approach entirely.

Notes for Paul

Optional / last priority. Useful if you want the more aggressive tiny position stripping and are willing to own the linker-patch cost; otherwise skip or discuss with mvdan first.