make sure travis fails when clippy does not build.

Fixes #3260

Author: matthiaskrgr

.travis.yml

@@ -57,11 +57,9 @@ script:
       export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib
   - |
     if [ -z ${INTEGRATION} ]; then
-      ./ci/base-tests.sh
-      sleep 5
+      ./ci/base-tests.sh && sleep 5
     else
-      ./ci/integration-tests.sh
-      sleep 5
+      ./ci/integration-tests.sh && sleep 5
     fi
 
 after_success: |