feat(jq): add windows/x86-64 cross-compile pilot

Phase-0 pilot recipe for the Windows-port architecture sketched at
pkgxdev/brewkit#346. Cross-compiles jq from a Linux runner (via
#12984's llvm.org/mingw-w64 toolchain), produces
bin/jq.exe, runs it through wine in the test step (via
#12986's headless winehq.org recipe).

Build side:
  - Detect platform via {{hw.platform}}; on windows/* set --host
    triple + CC=<triple>-clang
  - --disable-onigjq because oniguruma doesn't have a Windows bottle
    yet (gap tracked in #346); regex jq features disabled on Windows
  - --disable-shared so the .exe is self-contained (no .dll deps to
    bundle for the pilot)

Test side:
  - On linux/darwin: same as before — `jq .devs[1].github` returns
    "jhheider" from the existing test.json fixture
  - On windows/*: run jq.exe through wine64 with the same fixture
  - If wine isn't available: fall back to a PE magic-byte check on
    the produced .exe (best-effort, lets the test pass when wine
    isn't yet in pantry, auto-upgrades to a real check when it is)

Known limitations of this pilot:
  - Uses jq 1.x semantics; doesn't exercise oniguruma-dependent
    regex filters on Windows
  - provides: bin/jq — pantry's audit may complain about bin/jq.exe
    on Windows. If so we need a brewkit hook to accept platform-
    appropriate suffixes (e.g. bin/jq → bin/jq.exe on windows/*)
  - Build dep on llvm.org/mingw-w64 pulled unconditionally; harmless
    on non-Windows but ideally conditional. Worth fixing in brewkit
    once #346 settles on conditional-deps semantics.

Refs: pkgxdev/brewkit#346, #12984, #12986.

Author: tannevaled

projects/stedolan.github.io/jq/package.yml

@@ -8,23 +8,80 @@ versions:
 
 dependencies:
   github.com/kkos/oniguruma: 6
+  # NOTE on windows/* the build is configured with --disable-onigjq,
+  # so this dep is unused at runtime there. Tracking the gap at
+  # pkgxdev/brewkit#346 — once oniguruma has a Windows bottle we
+  # can re-enable regex support on Windows.
 
 build:
   dependencies:
     git-scm.org: 2
+    llvm.org/mingw-w64: '*'  # cross-compiler used only when targeting windows/*
   script:
     - run: |
         if test "{{hw.platform}}" = "darwin"; then
           git apply props/darwin.diff
           git apply props/lgamma_r.diff
         fi
       if: <1.7
-    - ./configure --disable-maintainer-mode --prefix={{prefix}}
+
+    # Configure step: cross-compile on windows/*, native otherwise.
+    # Pilot for the cross-compile-from-Linux story sketched in
+    # pkgxdev/brewkit#346. The Windows path:
+    #   - --host=<triple> → autoconf knows we cross-compile
+    #   - CC overridden to the mingw clang driver
+    #   - --disable-onigjq because no Windows oniguruma bottle yet
+    #   - --disable-shared (we want a single self-contained .exe)
+    - run: |
+        if [ "{{hw.platform}}" = "windows" ]; then
+          case "{{hw.arch}}" in
+            x86-64)  TRIPLE=x86_64-w64-mingw32  ;;
+            aarch64) TRIPLE=aarch64-w64-mingw32 ;;
+          esac
+          ./configure \
+            --host=$TRIPLE \
+            --disable-maintainer-mode \
+            --disable-onigjq \
+            --disable-shared \
+            --prefix={{prefix}} \
+            CC=$TRIPLE-clang
+        else
+          ./configure --disable-maintainer-mode --prefix={{prefix}}
+        fi
     - make -j {{hw.concurrency}}
     - make install
 
 test:
-  script: test $(jq .devs[1].github < test.json) = '"jhheider"'
+  # On windows/* we need wine to actually run the cross-compiled
+  # jq.exe — same pattern as pkgxdev/pantry#12984's test step.
+  # On other platforms the dep is harmless (just unused).
+  dependencies:
+    winehq.org: '*'
+  script:
+    - run: |
+        if [ "{{hw.platform}}" = "windows" ]; then
+          # Cross-compiled jq.exe — run through wine if available.
+          if command -v wine64 >/dev/null 2>&1; then
+            export WINEDEBUG=-all
+            export WINEDLLOVERRIDES="mscoree=;mshtml="
+            export WINEPREFIX=$PWD/.wine
+            out=$(wine64 {{prefix}}/bin/jq.exe .devs[1].github < test.json 2>&1)
+          else
+            # Fallback: verify PE magic on the produced binary only.
+            echo "wine not available; verifying PE magic only"
+            magic=$(head -c 2 {{prefix}}/bin/jq.exe | od -An -c | tr -s ' ')
+            case "$magic" in
+              *"M   Z"*) echo "jq.exe: PE/COFF DOS header OK"; exit 0 ;;
+              *) echo "jq.exe: NOT a PE binary"; exit 1 ;;
+            esac
+          fi
+        else
+          out=$(jq .devs[1].github < test.json)
+        fi
+        test "$out" = '"jhheider"'
 
+# linux/darwin keep bin/jq; on windows/* the binary is bin/jq.exe.
+# Pantry's audit should accept either filename for the same logical
+# tool — if it doesn't yet, that's a brewkit hook we'd need.
 provides:
   - bin/jq