docker: Use the interactive flag

Docker run without an --interactive flag causes containers to keep running in
the background if they're killed with control-c.

Change-Id: If184136526bbaafae196b0d7b484ae8c1f150334
diff --git a/docker.mk b/docker.mk
index 3a25286..96e37c5 100644
--- a/docker.mk
+++ b/docker.mk
@@ -60,7 +60,7 @@
 # Runs any make TARGET in x86 docker image ('m docker-TARGET')
 docker-%: docker-build;
 	docker load -i $(ROOTDIR)/cache/aiy-board-builder.tar
-	docker run --rm --privileged --tty \
+	docker run -i --rm --privileged --tty \
 		$(DOCKER_VOLUMES) \
 		$(DOCKER_ENV) \
 		-w /rootdir \