Add timeit.bat to tools\win

timeit.bat is a simple batch file that times whatever command you pass
to it. It uses a helper python script to do the math at the end. There
is no error checking so don't make mistakes.

R=dcheng@chromium.org

Review-Url: https://codereview.chromium.org/2820843002
Cr-Commit-Position: refs/heads/master@{#464815}
2 files changed