fix(Makefile): golint to new URL (#1592)

as title. Just update the golint to new URL.

Makefile

@@ -43,7 +43,7 @@ embedmd:
 .PHONY: lint
 lint:
 	@hash golint > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
-		go get -u github.com/golang/lint/golint; \
+		go get -u golang.org/x/lint/golint; \
 	fi
 	for PKG in $(PACKAGES); do golint -set_exit_status $$PKG || exit 1; done;