corrected log file wall time breakdown

The recent commit 873b9854 doubled the wall times in the breakdown
table in the log file when not using separate PME nodes.
Note that this didn't affect cycle count or total timing prints.
Fixes #1210

Change-Id: Ia2b1d5e6c21543990465b7c7a4a8a1e687c41528
Merge "corrected log file wall time breakdown" into release-4-6