Add PHPUnit (Doltlite) workflow

Build Doltlite from source and run the mysql-on-sqlite PHPUnit suite
against it via LD_PRELOAD, so PHP's PDO SQLite transparently uses the
Doltlite engine.

See: https://github.com/timsehn/doltlite

Author: JanJakes

.github/workflows/phpunit-tests-doltlite.yml

@@ -0,0 +1,77 @@
+name: PHPUnit Tests (Doltlite)
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  test:
+    name: PHP ${{ matrix.php }} / Doltlite
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php: [ '8.3' ]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install Doltlite build dependencies
+        run: sudo apt-get update && sudo apt-get install -y build-essential zlib1g-dev tcl-dev
+
+      - name: Check out Doltlite
+        uses: actions/checkout@v4
+        with:
+          repository: timsehn/doltlite
+          path: doltlite-src
+
+      - name: Build Doltlite shared library
+        run: |
+          mkdir -p build
+          cd build
+          ../configure
+          make -j"$(nproc)" doltlite-lib
+          ls -la libdoltlite* sqlite3.h
+        working-directory: doltlite-src
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '${{ matrix.php }}'
+          tools: phpunit-polyfills
+
+      - name: Verify Doltlite is wired up via LD_PRELOAD
+        env:
+          LD_PRELOAD: ${{ github.workspace }}/doltlite-src/build/libdoltlite.so
+        run: |
+          echo "ldd pdo_sqlite:"
+          ldd "$(php -r 'echo ini_get("extension_dir");')/pdo_sqlite.so" || true
+          echo
+          php -r '$v = (new PDO("sqlite::memory:"))->query("SELECT SQLITE_VERSION()")->fetch()[0]; echo "SQLITE_VERSION() = $v\n";'
+          echo "If Doltlite is active, the engine() check below should print 'prolly':"
+          php -r '$r = (new PDO("sqlite::memory:"))->query("SELECT doltlite_engine()")->fetch(); var_dump($r);' || true
+
+      - name: Install Composer dependencies (root)
+        uses: ramsey/composer-install@v3
+        with:
+          ignore-cache: "yes"
+          composer-options: "--optimize-autoloader"
+
+      - name: Install Composer dependencies (mysql-on-sqlite)
+        uses: ramsey/composer-install@v3
+        with:
+          working-directory: packages/mysql-on-sqlite
+          ignore-cache: "yes"
+          composer-options: "--optimize-autoloader"
+
+      - name: Run PHPUnit tests against Doltlite
+        env:
+          LD_PRELOAD: ${{ github.workspace }}/doltlite-src/build/libdoltlite.so
+        run: php ./vendor/bin/phpunit -c ./phpunit.xml.dist
+        working-directory: packages/mysql-on-sqlite