Make Thrift servers work on Windows
Make Thrift servers work on Windows

Summary:
Windows doesn't have fcntl so when trying to resolve the import it
resolves to None (Introduced in D4812541).

When running a Thrift server on Windows it crashes when trying to use fcntl.
Ignoring its usages for now since they are not hard dependencies for the
server to run.

Differential Revision: D5592196

fbshipit-source-id: 75e0fd5e5b26fa76648d13c5adfcc084cb112315

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