Persist the make cache

If we don't do this, the test job will try to rebuild everything.
That defeats the purpose.

Probably, we've got our Make dependencies/targets setup improprerly.

.circleci/config.yml

@@ -14,6 +14,10 @@ jobs:
       - run:
           name: Compile
           command: make build
+      - persist_to_workspace:
+          root: .make
+          paths:
+            - '*'
       - persist_to_workspace:
           root: dist
           paths:

Makefile

@@ -30,9 +30,6 @@ $(EMPTY)/build: $(EMPTY)/stack-setup README.md Setup.hs package.yaml stack.yaml
 	cp -R $$($(STACK) $(STACK_FLAGS) path --dist-dir)/build $(DIST)/build
 	touch $@
 
-$(EMPTY)/doc-test: $(EMPTY)/build
-	touch $@
-
 $(EMPTY)/stack-setup: | $(EMPTY)
 	$(STACK) $(STACK_FLAGS) setup
 	touch $@