Revert "Changed connect to async use of libpq on non-Windows OSes"

This reverts commit 45ccff4be6bcc8e0f4d70efdaf23a5028a50588c.

lpsmith/postgresql-simple#119 workaround

Revert "Change exec to async use of libpq on non-Windows OSes"

This reverts commit 83d3c38386af90690f56bb8501167bc74180b06b.