[LTP] [PATCH v2] travis: Use centos:7 instead of centos:6

[Petr Vorel]

> I have this idea when I meet ALG_SET_AEAD_ASSOCLEN undefined error on centos7.
> It is more friendly for centos7 user and more meaningful. centos6 is outdated
> and we should drop it.

> Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

> ---
>  .travis.yml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

> diff --git a/.travis.yml b/.travis.yml
> index e8e3189af..3c5ff99b7 100644
> --- a/.travis.yml
> +++ b/.travis.yml
> @@ -44,7 +44,7 @@ matrix:
>            compiler: clang

>          - os: linux
> -          env: DISTRO=centos:6 TREE=out
> +          env: DISTRO=centos:7 TREE=out
>            compiler: gcc

>          - os: linux