fix encoding bug
fix encoding bug

Summary: This bug can be triggered when your computer name contains emoji. getdeps.py will fail to create this file due to Python attempts to write the file as cp1252 (Windows's default encoding)

Reviewed By: wez

Differential Revision: D22171935

fbshipit-source-id: fc3be2d1050c17ddbe05a0fc91d6613865f092ce

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