CI: add minimal-ci

.github/workflows/minimal-ci.yml

@@ -0,0 +1,28 @@
+# minimal GitHub CI building UPX with clang and gcc in an Alpine Linux container
+
+name: 'Minimal CI with Alpine Linux'
+
+on: { workflow_dispatch: }
+jobs:
+  job-alpine-cmake:
+    strategy: {matrix: {container: ['alpine:3.12','alpine:3.17','alpine:edge']}}
+    name: ${{ format('container {0}', matrix.container) }}
+    runs-on: ubuntu-latest
+    container: ${{ matrix.container }}
+    steps:
+      - name: ${{ format('Install packages {0}', matrix.container) }}
+        run: 'apk update && apk upgrade && apk add bash clang cmake g++ git make'
+      - name: 'Check out code'
+        run: |
+          git clone --branch devel --depth 1 https://github.com/upx/upx
+          git -C upx submodule update --init
+          echo 'artifact_name=upx-minimal-ci-${{ matrix.container }}' | sed 's/:/-/g' >> $GITHUB_ENV
+      - { name: 'Build clang', run: 'make -C upx build/extra/clang/release' }
+      - { name: 'Build gcc',   run: 'make -C upx build/extra/gcc/release' }
+      - name: ${{ format('Upload artifact {0}', env.artifact_name) }}
+        uses: actions/upload-artifact@v3
+        with:
+          name: ${{ env.artifact_name }}
+          path: 'upx*/build/*/*/*/upx'
+      - { name: 'Run basic tests clang', run: 'make -C upx/build/extra/clang/release test' }
+      - { name: 'Run basic tests gcc',   run: 'make -C upx/build/extra/gcc/release test' }