travis: set the pipefail option

The travis job has to fail if make smoke-test fails.

Reported-by: Bin Lu <bin.lu@arm.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>

.travis.yml

@@ -16,7 +16,7 @@ script:
    # On arm64, we need to create our own pipes for stderr and stdout,
    # otherwise we will not be able to open /dev/stderr. This is probably
    # due to AppArmor rules.
-   - uname -a && make smoke-test 2>&1 | cat
+   - bash -xeo pipefail -c 'uname -a && make smoke-test 2>&1 | cat'
 branches:
   except:
   # Skip copybara branches.