Add FreeBSD CI (verification run, do not merge)

.github/workflows/test_other_platforms.yml

@@ -0,0 +1,64 @@
+name: Test on other platforms
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  freebsd:
+    name: FreeBSD ${{ matrix.release }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 120
+    strategy:
+      fail-fast: false
+      matrix:
+        release: ["15.1", "13.5"]
+
+    steps:
+      - name: Checkout MoarVM
+        uses: actions/checkout@v7
+        with:
+          path: MoarVM
+          submodules: recursive
+          fetch-depth: 0
+          fetch-tags: true
+          persist-credentials: false
+
+      - name: Build and probe in FreeBSD
+        uses: vmactions/freebsd-vm@v1
+        with:
+          release: ${{ matrix.release }}
+          usesh: true
+          copyback: false
+          cache-after-prepare: true
+          prepare: |
+            pkg install -y perl5 gmake git-lite
+          run: |
+            set -e
+            git config --global --add safe.directory '*'
+            cd MoarVM
+
+            perl -0pi -e 's|#include <util\.h>|#if defined(__FreeBSD__)\n#include <libutil.h>\n#else\n#include <util.h>\n#endif|' \
+              3rdparty/libuv/src/unix/process.c
+
+            echo "===== patch FreeBSD syslibs: add util ====="
+            perl -0pi -e 's/(%OS_FREEBSD = \(.*?qw\( kvm) \)/$1 util )/s' build/setup.pm
+            echo "--- FreeBSD block now reads: ---"
+            perl -0ne 'print $1 if /(my %OS_FREEBSD = \(.*?\n\);)/s' build/setup.pm
+
+            echo "===== build ====="
+            perl Configure.pl --toolchain=gnu --compiler=clang --prefix=../install
+            gmake install
+            ../install/bin/moar --version
+
+            echo "===== does libmoar.so link libutil now? ====="
+            ldd ../install/lib/libmoar.so | grep libutil && echo "LINKED: libutil" || echo "STILL NOT LINKED"
+            echo "===== is openpty still unresolved? ====="
+            nm -D --undefined-only ../install/lib/libmoar.so | grep -w openpty \
+              && echo "still listed as undefined (expected: it now resolves via libutil at runtime)" \
+              || echo "openpty no longer undefined"