[PATCH] travis: Update to Xenial environment

[Nir Soffer]

From: Nir Soffer

Current Trusty based environment fail to complile with:

cc: error: unrecognized command line option ‘-fstack-protector-strong’
    cc: error: unrecognized command line option ‘-fstack-clash-protection’

Upgrading to Xenial fix the first issue. I guess we need to check
availability of the second flag, or switch to build inside a container.

Signed-off-by: Nir Soffer 
---
 .travis.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.travis.yml b/.travis.yml
index 9668e82..675768d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,13 @@
+dist: xenial
 language: python

before_install:
     - sudo apt-get -qq update
     - sudo apt-get install -y make gcc libaio-dev libblkid-dev

script:
     - make -C wdmd
     - make -C src
     - make -C python inplace
     - source tests/env.sh
     - pytest