Add a 'time' command

[Sascha Hauer]

The time command was useful during MMU rework as it allowed me
to measure the impacts of caching. Unfortunately the timer
may overrun during execution of the command, so the result may
not be correct. Still I find this useful enough to be part
of barebox.

Sascha

Sascha Hauer (2):
      memcpy command: allow to interrupt
      Add 'time' command to measure execution time of a command

 commands/Kconfig  |   10 +++++++++
 commands/Makefile |    1 +
 commands/mem.c    |    3 ++
 commands/time.c   |   57 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+), 0 deletions(-)
 create mode 100644 commands/time.c