.travis.yml: perform 'make distcheck'
.travis.yml: perform 'make distcheck'

This will ensure having the autotools files always up to date.

Signed-off-by: Enrico Jorns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

rauc/rauc,ejoerns/rauc,rauc/rauc,jluebbe/rauc,rauc/rauc,jluebbe/rauc,jluebbe/rauc,ejoerns/rauc,ejoerns/rauc