CLOG_mergelogs - merge individual logfiles into one via messages
void CLOG_mergelogs( shift, execfilename, logtype )
first argument says whether to do time-shifiting or not second arg is
On process 0 in MPI_COMM_WORLD, collect logs from other processes and
merge them with own log. Timestamps are assumed to be already adjusted
on both incoming logs and the master’s. On the other processes, fill
in length and process id’s and send them, a block at a time, to the
master. The master writes out the merged log.