Don't install to /var/cache

--- a/Makefile.am
+++ b/Makefile.am
@@ -156,7 +156,6 @@ install-exec-hook:
 		echo "$(CACHEDIR) already exists."; \
 	else \
 		echo "Creating cache in $(CACHEDIR)."; \
-		mkdir -p $(CACHEDIR) || true; \
 	fi
 
 uninstall-hook: