With the recent patches, criu is finally compileable with
clang for all architectures. To keep it that way, we need
Travis to test that on a regular basis.

The downside is, Travis build time is increased about 2x.

travis-ci: success for travis: enable arm/arm64/ppc builds with clang
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>