Add static link to CI

so we can track it and when it breaks

.travis.yml

@@ -19,7 +19,8 @@ env:
     - DOCKER_PACKAGES="build-essential cmake git libcap-dev bsdmainutils curl git ca-certificates ccache"
   matrix:
       #- HOST=x86_64-w64-mingw32
-      - HOST=x86_64-unknown-linux-gnu
+      - HOST=x86_64-unknown-linux-gnu STATIC_LINK=OFF
+      - HOST=x86_64-unknown-linux-gnu STATIC_LINK=ON
       #- HOST=x86_64-apple-darwin11 OSX_SDK=10.12
 install:
     - env | grep -E '^(CCACHE_|DISPLAY|CONFIG_SHELL)' | tee /tmp/env
@@ -37,7 +38,7 @@ script:
   - OUTDIR=$BASE_OUTDIR/$TRAVIS_PULL_REQUEST/$TRAVIS_JOB_NUMBER-$HOST
   - if [ -z "$NO_DEPENDS" ]; then $DOCKER_EXEC ccache --max-size=$CCACHE_SIZE; fi
   #- $DOCKER_EXEC bash -c "update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-6"
-  - $DOCKER_EXEC bash -c "mkdir build && cd build && cmake .. && make $MAKEJOBS && make test"
+  - $DOCKER_EXEC bash -c "mkdir build && cd build && cmake .. && make $MAKEJOBS STATIC_LINK=$STATIC_LINK && make test"
 after_script:
   - echo $TRAVIS_COMMIT_RANGE
   - echo $TRAVIS_COMMIT_LOG