HPCC-9326 - onStartCalled not set if nullact causing assert

A null act was bypassing normal initialization, but also
bypassing setting onStartCalled to true. As a result a null act
in a child query was hitting an assert during initialization

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #4376 from jakesmith/hpcc-9326

HPCC-9326 - onStartCalled not set if nullact causing assert

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>