Add CI testing for musl

.github/workflows/ci.yml

@@ -110,4 +110,105 @@ jobs:
     - name: Build and test distribution
       run: make distcheck
 
+  test-musl:
+    runs-on: ubuntu-latest
+    container: alpine:latest
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install dependencies
+      run: |
+        apk add --no-cache \
+          build-base \
+          autoconf \
+          automake \
+          perl \
+          patch \
+          diffutils \
+          xmlto \
+          pcre2-dev \
+          bash \
+          git \
+          coreutils \
+          python3
+
+    - name: Clone gnulib for bootstrap
+      run: |
+        git clone --depth 1 https://git.savannah.gnu.org/git/gnulib.git /tmp/gnulib
+
+    - name: Bootstrap
+      run: |
+        export PATH="/tmp/gnulib:$PATH"
+        ./bootstrap
+
+    - name: Configure
+      run: ./configure --with-pcre2
+
+    - name: Build
+      run: make -j$(nproc)
+
+    - name: Run tests
+      run: make check
+
+    - name: Show test results on failure
+      if: failure()
+      run: |
+        echo "=== Test logs ==="
+        find . -name "*.log" -type f -exec echo "=== {} ===" \; -exec cat {} \;
+        echo "=== Test arena contents ==="
+        find test-arena -type f 2>/dev/null | head -20 | while read f; do
+          echo "=== $f ==="
+          cat "$f" 2>/dev/null || echo "Cannot read file"
+        done
+
+  test-musl-without-pcre2:
+    runs-on: ubuntu-latest
+    container: alpine:latest
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install dependencies (without PCRE2)
+      run: |
+        apk add --no-cache \
+          build-base \
+          autoconf \
+          automake \
+          perl \
+          patch \
+          diffutils \
+          xmlto \
+          bash \
+          git \
+          coreutils \
+          python3
+
+    - name: Clone gnulib for bootstrap
+      run: |
+        git clone --depth 1 https://git.savannah.gnu.org/git/gnulib.git /tmp/gnulib
+
+    - name: Bootstrap
+      run: |
+        export PATH="/tmp/gnulib:$PATH"
+        ./bootstrap
+
+    - name: Configure without PCRE2
+      run: ./configure --without-pcre2
+
+    - name: Build
+      run: make -j$(nproc)
+
+    - name: Run tests
+      run: make check
+
+    - name: Show test results on failure
+      if: failure()
+      run: |
+        echo "=== Test logs ==="
+        find . -name "*.log" -type f -exec echo "=== {} ===" \; -exec cat {} \;
+        echo "=== Test arena contents ==="
+        find test-arena -type f 2>/dev/null | head -20 | while read f; do
+          echo "=== $f ==="
+          cat "$f" 2>/dev/null || echo "Cannot read file"
+        done
+