travis-ci: update gcc version
travis-ci: update gcc version

jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,jvf/scalaris