.github: build leg without D-Bus

The D-Bus support is default-enabled, so the HAVE_DBUS paths only
bit-rot silently without this: the leg caught initctl failing to
build with --disable-dbus on its first local run.  Also asserts the
binaries carry no bus references and smoke-runs one non-dbus test.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/build.yml

@@ -149,3 +149,42 @@ jobs:
         with:
           name: finit-test-${{ matrix.compiler }}
           path: test/*.log
+
+  no-dbus:
+    # The D-Bus support is default-enabled, so the HAVE_DBUS paths in
+    # initctl and finit only bit-rot silently without this leg.
+    name: no-dbus
+    runs-on: ubuntu-latest
+    if: github.event_name != 'push' || github.ref == 'refs/heads/master'
+    steps:
+      - name: Install dependencies
+        run: |
+          sudo apt-get -y update
+          sudo apt-get -y install pkg-config tree jq libcap-dev libconfuse-dev libblkid-dev
+          wget https://github.com/troglobit/libuev/releases/download/v2.4.1/libuev-2.4.1.tar.xz
+          wget https://github.com/troglobit/libite/releases/download/v2.6.2/libite-2.6.2.tar.gz
+          tar xf libuev-2.4.1.tar.xz
+          tar xf libite-2.6.2.tar.gz
+          (cd libuev-2.4.1 && ./configure && make -j9 && sudo make install-strip)
+          (cd libite-2.6.2 && ./configure && make -j9 && sudo make install-strip)
+          sudo ldconfig
+      - uses: actions/checkout@v7
+      - name: Build without D-Bus
+        run: |
+          ./autogen.sh
+          ./configure --prefix=/usr --exec-prefix= --sysconfdir=/etc --localstatedir=/var \
+                      --disable-dbus --enable-testserv-plugin --with-keventd
+          make -j9 V=1
+      - name: Verify no bus artifacts
+        run: |
+          DESTDIR=/tmp make install-strip
+          ! strings /tmp/sbin/initctl | grep -q finit/bus
+          ! strings /tmp/sbin/finit   | grep -q org.finit
+      - name: Enable unprivileged userns (unshare)
+        run: |
+          sudo sysctl kernel.apparmor_restrict_unprivileged_userns=0
+      - name: Smoke test
+        run: |
+          make -C test setup-chroot
+          make -j1 -C test check TESTS='start-stop-serv.sh' \
+              || (cat test/test-suite.log; false)