setup COMPILER_ID/HHVM_REPO_SCHEMA so it doesn't look it up from our package git repo

test:
$ hhvm  --compiler-id
tags/HPHP-2.1.0-78394ee3f8c332eabdd97a3970f356b3ce70aacb
$ hhvm  --repo-schema
059341548_1381096940
build with internal folly