hack/build: Add the local vendor directory for generate

Because 'go run' ignores vendor/ otherwise [1].

[1]: golang/go#20406

Author: wking

hack/build.sh

@@ -10,7 +10,7 @@ TAGS=
 case "${MODE}" in
 release)
 	TAGS=release
-	go generate ./data
+	GOPATH="${PWD}/vendor:${GOPATH}" go generate ./data
 	;;
 dev)
 	;;