remove frontend dependency

Makefile

@@ -45,7 +45,7 @@ case_studies.proof:	$(CASE_STUDIES:=.proof)
 clean_case_studies: $(CASE_STUDIES:=.clean)
 .PHONY: clean_case_studies
 
-generate_case_studies: frontend
+generate_case_studies:
 generate_case_studies: $(CASE_STUDIES:=.crate)
 .PHONY: generate_case_studies
 
@@ -61,14 +61,14 @@ clean_stdlib:
 	RUST_PATH=$(RUST_PATH) $(MAKE) -C stdlib clean_stdlib
 .PHONY: clean_stdlib
 
-generate_stdlib: frontend
+generate_stdlib:
 	RUST_PATH=$(RUST_PATH) $(MAKE) -C stdlib generate_stdlib
 .PHONY: generate_stdlib
 
 ### Calling the frontend
 # this adds the path to the built frontend so cargo can find it
 %.crate:	export PATH := $(CURDIR)/rr_frontend/$(RUST_PATH):$(PATH)
-%.crate: % frontend
+%.crate: %
 	cd $* && cargo refinedrust
 
 %.clean: phony