Change rate measurement code.

Change rate measurement code.

For %o, remove a superfluous + 0.5: snprintf("%f") rounds already.
Remove some unnecessary code.

For %c, fix a TODO to add a sliding window and update after every
completed edge. Else, with -j50 and several files that take 3s to
compile each, this number would only update every 150s. Also give
the number one decimal place so that this can measure steps slower
than 1s.