CHROMIUM: minor polish for system mounts

Improve `mount` output to not use "none" for important /sys & /proc.

BUG=chromium:1063545
TEST=CQ passes

Change-Id: I5938f03fd659ce2eeadf2a314e839ecfd1c8177c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/upstart/+/2545883
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
Reviewed-by: Allen Webb <allenwebb@google.com>
1 file changed