travis: use container build

Travis offers two build environments: fully virtualised, container.

Until recently the container version didn't have all the libraries that we
needed.  Now it does.

The container is much faster to start up: <1s rather that ~20s.

diff --git a/.travis.yml b/.travis.yml
index b0b7225c3979b258be50bf7c1109ad9bb924d123..81fdfb4463029045519d58bacd27c503c8cc73d2 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,7 +5,7 @@ notifications:
     on_success: change
     on_failure: always
 
-sudo: required
+sudo: false
 dist: trusty
 
 language: c