Add --noclean option to avoid cleaning build root.

The --noclean option is useful for testing changes in a chroot without
blowing away local changes.

BUG=chromium-os:17659
TEST=Test that my changes aren't blown away when I use --noclean.

Change-Id: I2968de0e252bf10b2af7c71574b4d734e2ca3a19
Reviewed-on: http://gerrit.chromium.org/gerrit/4207
Reviewed-by: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
1 file changed