GitLab

Always log kernel serial output to a temporary file on the host, so that
if we're unable to establish connectivity to the QEMU guest then we can
dump the contents of that file for diagnostic use.

Bug: 909936, 869753
Change-Id: Ie44ea6f6d0ccaedbae6994651ec13568ad241a40
Reviewed-on: https://chromium-review.googlesource.com/c/1359483Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613393}