tests: add `set -e` specifier to bail early on build run

Seems that test1 is failing, but travis is not catching it.
Likely, this is because the `cppcheck` returns success
and we need to bail on the `make check` step.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

.travis.yml

@@ -16,6 +16,7 @@ os:
 before_install:
   - echo $LANG
   - echo $LC_ALL
+  - set -e
 
 install:
   - sh autogen.sh