add manifest for re2
add manifest for re2

Summary: needed for openr

Reviewed By: simpkins

Differential Revision: D16010070

fbshipit-source-id: 6d485fa7e4e321e6cd23d9894b38c1ecc7574665

rsocket/rsocket-cpp,rsocket/rsocket-cpp,ReactiveSocket/reactivesocket-cpp,ReactiveSocket/reactivesocket-cpp,ReactiveSocket/reactivesocket-cpp,rsocket/rsocket-cpp,rsocket/rsocket-cpp