Makefile is out-of-date with caravel_user_project Makefile

[d-m-bailey]

In particular, the setup-timing-scripts target won't work because these settings are not included.

export CUP_ROOT=$(shell pwd)
export TIMING_ROOT?=$(shell pwd)/dependencies/timing-scripts
export PROJECT_ROOT=$(CUP_ROOT)
timing-scripts-repo=https://github.com/efabless/timing-scripts.git

$(TIMING_ROOT):
	@mkdir -p $(CUP_ROOT)/dependencies
	@git clone $(timing-scripts-repo) $(TIMING_ROOT)