Fix SControl socket portability on Linux

[caseychaos1212]

Summary

• replace Windows-only socket address types in SControl
• use platform-appropriate socket length types
• replace Sleep(0) with std::this_thread::yield()
• use the existing cross-platform socket error abstraction
• add scontrol to the Linux CI target list

Verification

• built scontrol with RelWithDebInfo on Linux
• built scontrol with Debug on Linux
• built the expanded Linux CI baseline successfully