Add CI job for default bindings

Author: wetneb

.github/workflows/CI.yml

@@ -6,11 +6,17 @@ jobs:
   test:
     name: rust-libxml CI
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        with_default_bindings: [false, true]
     steps:
       - name: install dependencies
         uses: ryankurte/[email protected]
         with:
           packages: "libxml2-dev"
+      - name: Set up LIBXML2 env var if compiling with the default bindings
+        run: echo "LIBXML2=$(pkg-config libxml-2.0 --variable=libdir)/libxml2.so" >> "$GITHUB_ENV"
+        if: ${{ matrix.with_default_bindings }}
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
@@ -20,4 +26,4 @@ jobs:
       - name: run tests
         uses: actions-rs/cargo@v1
         with:
-          command: test
+          command: test