jenkins-common.sh: exit if image fails to build

docker_images_require() must fail when a new image can not be built,
even if an old image already exists.

We have this situation in a lot of the -latest tests right now, which
makes it harder to find the actual error.

Note that we can't simply use #!/bin/sh -e in all the jenkins.sh
scripts that source jenkins_common.sh, because they must be able to
clean up the docker containers on failure. So they can't abort
somewhere in the middle of the scripts. We could rewrite them to do the
clean up in a trap, but this should be done in a separate commit.

Related: OS#3767
Change-Id: I7039089457b62b8798a79c5efd62bd91622986d3

jenkins-common.sh

@@ -7,10 +7,10 @@ docker_images_require() {
 		# Trigger image build (cache will be used when up-to-date)
 		if [ -z "$NO_DOCKER_IMAGE_BUILD" ]; then
 			echo "Building image: $i (export NO_DOCKER_IMAGE_BUILD=1 to prevent this)"
-			make -C "../$i"
+			make -C "../$i" || exit 1
 		fi
 
-		# Detect missing images (build skipped/failure)
+		# Detect missing images (build skipped)
 		if ! docker_image_exists "$i"; then
 			echo "ERROR: missing image: $i"
 			exit 1