travis: test upstart/systemd init script handling

Enable testing of both the upstart and systemd init script handling.
We test a different one in each scenario. Even though trusty only
cares about upstart, it is fine for us to test rules that install
systemd, since we're not actually running these scripts for real.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

.travis.yml

@@ -6,8 +6,12 @@ matrix:
   include:
     - compiler: gcc
       dist: trusty
+      env:
+        - DISTCHECK_CONFIGURE_FLAGS="--with-init-script=upstart"
     - compiler: clang
       dist: trusty
+      env:
+        - DISTCHECK_CONFIGURE_FLAGS="--with-init-script=systemd"
     - compiler: clang
       os: osx
       script:
@@ -99,7 +103,7 @@ before_script:
   - ./autogen.sh --prefix=$(pwd)/install-root
 
 script:
-  - make -j3 && make -j3 syntax-check && make -j3 distcheck
+  - make -j3 && make -j3 syntax-check && make -j3 distcheck DISTCHECK_CONFIGURE_FLAGS=$DISTCHECK_CONFIGURE_FLAGS
 
 after_failure:
   - echo '============================================================================'