travis.yml: Move ./configure to before_script
travis.yml: Move ./configure to before_script

This way, the Travis build will error and not fail on missing
dependencies.

Signed-off-by: Quentin Glidic <241385a0e41ea713327e189bce1062decf7c1eb5@sardemff7.net>

carnager/rofi,carnager/rofi,carnager/rofi