Additional attempts to flosh stdout/stderr

The logfile output is piped through awk to apply a timestamp
and filter out all of the xtrace commands in the xtrace output.

A while back we added fflush("") which is supposed to flush all
open output files and pipes. It appears that gawk in precise
is old enough that it may only flush stdout, so explicitly
flush the logfile handle.

Change-Id: If5198c2da2a3278eed8ae3d50c7ca5c15eac6d94

stack.sh

@@ -541,6 +541,7 @@ if [[ -n "$LOGFILE" ]]; then
                     print
                     print > logfile
                     fflush("")
+                    fflush(logfile)
                 }' ) 2>&1
         # Set up a second fd for output
         exec 6> >( tee "${SUMFILE}" )