Use Python standard library functionality instead of the time utility
for measuring elapsed (wall clock) time of commands. The time.* log
files are also ditched. However, the same detailed resource usage data,
previously found in time.* logs is now provided in results.json file.
This data is collected through the resource module of Python.
Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
