Protect IOVSvcTool against concurrent incident handler calls.
requested to merge goetz/athena:IOVSvcTool_master_protect_against_concurrent_incident_handler_calls into 22.0
The incident handler of the IOVSvcTool modifies and accesses internal maps. In MT these operations may happen concurrently and need to be mutex protected.
Addresses ATLASRECTS-7120.
Edited by Goetz Gaycken