formulae: use SDK-owned cross-compilation settings - #106

Why

Kandelo cross-compiles packages for WebAssembly, so many upstream configure scripts cannot run their normal probe programs on the build machine. The Kandelo SDK supplies reviewed answers about the target in sdk/config.site.

Nine Formulae also carried 21 local assignments covering 15 distinct target facts. Two copies can drift: the SDK could say a function is unavailable while a package recipe says it is available, causing packages to build under inconsistent assumptions. Package authors should receive one target contract from the SDK instead of maintaining private copies.

What changed

Remove the SDK-owned configure answers from Gawk, Grep, Gzip, Libpng, M4, Make, Nano, Sed, and XZ.

GNU Make deliberately retains make_cv_synchronous_posix_spawn=yes. That Make-specific probe checks whether a missing child reports ENOENT synchronously. It is package behavior, not a reusable function-availability fact.

No Formula revision is bumped. The candidate SDK supplies the same target answers before these lines are removed, so this changes ownership rather than intended package behavior. This PR contains no bottle block, archive, sidecar, receipt, provenance file, generated Wasm artifact, platform code, or Kandelo ABI change.

ABI 41 review evidence

• Exact tap base: a7d0d8ad92998a08a8bf1b03278e2189c01c2a0d
• Exact PR head: 89bfdeed1d4d5a13ff51b6bce3406b579c5728f5
• Tree: a77203cbc989cd257e1d6d3961cd2ceb76d869ce
• Stable zero-context patch identity: a9a2a2092dedf8c7b8c2e35f06430489cd1d3c1e
• Kandelo platform: ABI 41 merged main commit 6efb411f15df83819a4e21a961845084f8860f6c, tree b133bfa018f7e2bc84c4845edf2f945b2f844954, and sdk/config.site blob d8ea6e3f359419b004274784676db573ee08416c

Fresh checks covered all nine Formulae:

• Ruby syntax and canonical source closure passed for every Formula.
• Formula-support Ruby suite passed: 48 tests / 380 assertions.
• Formula-support TypeScript suite passed: 15 / 15 tests.
• SDK configure suite passed: 13 / 13 tests, and all 15 unique SDK-owned values match the values removed here.
• Gawk, Grep, Gzip, Libpng, M4, Make, Nano, Sed, and XZ all built from upstream source and passed their complete Formula tests.
• Supporting Zlib, Dash, Libcxx, and Ncurses dependencies were built from source at ABI 41.
• The captured config.log files show the candidate SDK and sdk/config.site supplied the cross-target answers.
• Receipts and dependency scans show no Kandelo registry package or undeclared build-dependency bridge.
• git diff --check passed.

This is source-build evidence. It does not claim that public bottles have been published, poured from GHCR, assembled into a VFS image, or run by stock Homebrew inside a guest.

Ordering and remaining gates

Automattic/kandelo#967 has merged. Its exact merged sdk/config.site blob matches all 15 facts removed here. This commit was restacked without patch changes onto current tap main; range-diff, stable patch identity, and the Formula blobs are unchanged. A final independent review found no code blocker.

Merge only after the fresh trust checks pass on the exact head above. Bottle publication remains a separate trusted-publisher operation with public readback, stock pour evidence, and Node.js/Chromium runtime validation.