github: add mkosi-based tests (freestanding mode)

Based on #77

Signed-off-by: Ariadne Conill <[email protected]>

Author: kaniini

.github/workflows/mkosi-tests.yaml

@@ -0,0 +1,39 @@
+name: Build and test libucontext (meson + mkosi)
+
+on:
+  pull_request:
+  push:
+
+permissions:
+  contents: read
+
+jobs:
+  mkosi:
+    runs-on: ${{matrix.runner}}
+    concurrency:
+      group: ${{ github.workflow }}-${{ matrix.distro }}-${{ github.ref }}-${{ matrix.runner }}
+      cancel-in-progress: true
+    strategy:
+      fail-fast: false
+      matrix:
+        - distro: [arch, debian, fedora, centos, opensuse]
+        - runner: [ubuntu-24.04, ubuntu-24.04-arm]
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: systemd/mkosi@d45142e329550abc9c6fc63c1f1f86e5286d3d67
+
+      - name: Configure
+        run: |
+          tee mkosi/mkosi.local.conf <<EOF
+          [Build]
+          ToolsTreeDistribution=${{ matrix.distro }}
+          EOF
+      - name: Setup
+        run: mkosi -f box -- meson setup build -Dfreestanding=true
+
+      - name: Build
+        run: mkosi -f box -- meson compile -C build
+
+      - name: Test
+        run: mkosi -f box -- meson test -C build --print-errorlogs

mkosi.conf

@@ -0,0 +1,4 @@
+[Build]
+CacheDirectory=mkosi.cache
+ToolsTree=default
+ToolsTreeProfiles=misc,devel