Travis docker ptrace fix (related to #145).

.travis.yml

@@ -24,5 +24,5 @@ before_install:
   - docker pull ${DOCKER_IMG}/${COMPILER}:stable
 
 script:
-  - docker run -v ${PWD}:/mnt -it ${DOCKER_IMG}/${COMPILER} /bin/bash -c "cd /mnt; script/ci_build.sh"
+  - docker run --cap-add SYS_PTRACE -v ${PWD}:/mnt -it ${DOCKER_IMG}/${COMPILER} /bin/bash -c "cd /mnt; script/ci_build.sh"