make_chroot: support pixz for decompression

For a speed up on decompression, use pixz when available.  We need to
tweak the decompression command slightly to workaround misbehavior --
it will try to decompress the file in place instead of stdout.

BUG=chromium:906289
TEST=creating new chroot still works

Change-Id: I25b1a867f4663dd6faea97ab849dc19906eecf12
Reviewed-on: https://chromium-review.googlesource.com/1387714
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
1 file changed