attempt to capture core dump from osmo-stp during ttcn3-bsc-test run

When launching osmo-stp-master from ttcn3-bsc-test, set ulimit=-1 to allow core
files.

In osmo-stp-master set WORKDIR to /data to hopefully get the core file ending
up there without the need to set a /proc/sys/kernel/core_pattern globally in
the jenkins slave.

Change-Id: Idd67fcb3f564b9cff9b4596bf639ed1bd1b58daf

osmo-stp-master/Dockerfile

@@ -38,7 +38,7 @@ RUN	case "$DISTRO" in \
 		;; \
 	esac
 
-WORKDIR	/tmp
+WORKDIR	/data
 
 ARG	OSMO_STP_BRANCH="master"
 

ttcn3-bsc-test/jenkins.sh

@@ -24,6 +24,7 @@ docker run	--rm \
 		--network $NET_NAME --ip 172.18.2.200 \
 		-v $VOL_BASE_DIR/stp:/data \
 		--name ${BUILD_TAG}-stp -d \
+		--ulimit core=-1 \
 		$DOCKER_ARGS \
 		$REPO_USER/osmo-stp-$IMAGE_SUFFIX