add option to pass options to `git clone`
add option to pass options to `git clone`

Summary: We need this for dependencies that require submodules

Reviewed By: saifhhasan, GirasoleY

Differential Revision: D15282792

fbshipit-source-id: b0cc8d645e73668252409934fd6741fb211e30ae

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