[travis] change to build folder before building

Author: m-kuhn

.ci/travis/linux/script.sh

@@ -29,7 +29,9 @@ export LD_PRELOAD=/lib/x86_64-linux-gnu/libSegFault.so
 
 export CTEST_BUILD_COMMAND="/usr/bin/make -j3 -i -k"
 
+pushd build
 $CTEST_BUILD_COMMAND
+popd
 
 python ${TRAVIS_BUILD_DIR}/.ci/travis/scripts/ctest2travis.py \
   xvfb-run ctest -V -E "$(cat ${DIR}/blacklist.txt | sed -r '/^(#.*?)?$/d' | paste -sd '|' -)" -S ${DIR}/../travis.ctest --output-on-failure