Summary:
Enrich the domain of SIOF to contain, as well as the globals needed by a
procedure, the globals that the procedure initializes. Also add the possibility
to model some procedures as initializing some variables. Use that mechanism to
teach the checker about `std::ios_base::Init`.
Reviewed By: mbouaziz
Differential Revision: D4588284
fbshipit-source-id: d72fc87