lint, mark the /* FALLTHROUGH */ case.
Info 768: global struct member 'aggregated' (line 124, file
wtperf.h) not referenced
Remove unnecessary __wt_epoch() call, the indentation makes it look
like an accident.
Remove another unnecessary __wt_epoch call; now that we're no longer
switching back-and-forth between time structures, rename them to
"start" and "stop" and get rid of the pointer versions.