mkdir  in docker_build.sh
mkdir  in docker_build.sh

Bug: skia:
Change-Id: I2f491c4e8c98325359021b661e6f2d1eddd55b9d
Reviewed-on: https://skia-review.googlesource.com/138992
Reviewed-by: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot