Depend on build when using the docker images.

docker/cargo_fmt/Makefile

@@ -28,9 +28,9 @@ endif
 
 # NOTE: This target will write to folders underneath the git-root
 .PHONY: run
-run:
+run: build
 	docker run --rm --init -v "$$(readlink -f ../../):/source" --workdir=/source $(IMAGE_NAME)
 
 .PHONY: shell
-shell:
+shell: build
 	docker run --rm -i -t --entrypoint /bin/sh -v "$$(readlink -f ../../):/source" --workdir=/source $(IMAGE_NAME)