rpc backend: fix makefile

support/rpc/Makefile

@@ -1,5 +1,3 @@
-IVORY_REPO ?= ../../../ivory
-
 default:
 	cabal build
 
@@ -8,4 +6,4 @@ create-sandbox:
 	cabal install --enable-tests --dependencies-only
 
 test:
-	cabal run -- --src-dir=codegen-out
+	@echo "RPC backend has no test suite."