Prepare for Gaudi v40

• Adapted to IAlgExecState change of interface in Gaudi (gaudi/Gaudi!1762 (merged))
• Adapted to change of properties in EventLoopMgr (gaudi/Gaudi!993 (merged))

Required for Gaudi v40, but working with Gaudi v39.

See LHCb!5179 (merged) for a detailed description.