Fix for build server

- Kokoro's repo_config style checkout doesn't actually do linkfile
rules. Thus, when the update tarball script runs make, it throws an
error due to no makefile existing, even though commands like m work.
- Add a -f build/Makefile parameter to the make invocations, so that the
Makefile being linked into the rootdir doesn't actually matter.

Change-Id: I8158d5e174c5be57b13e9170dd5538644410eb20
1 file changed