* Prevent TerminateAllChildProcesses from being called before listeners have been disposed. This was terminating ectool before it had finished updating properties.
* Propagate exit code from child process as the exit code for BuildAgent.exe.
* Write EC XML output to a temporary file and move it into place, to fix issues where a job was aborted mid-write.
#rb none
#rnx
[CL 9391349 by Ben Marsh in Dev-Build branch]
