--stats=%R
Currently we measure the time with clock_gettime() and report it with %r.
It would be nice to have another way to measure time, using times(), and to report it with %R. We could also have option %[u]R and %[s]R for restricing the output to user and system time, and maybe %[u!]R, %[s!]R, %[!]R for restricting the time to the current process (without its children).