Allow mounting of a tmpfs /tmp in the chroot

Added the -t option to minijail so a tmpfs can be used
in the chroot

BUG=chromium:356246
TEST=Tested with autotest security_Minijail0
CQ-DEPEND=CL:201147

Change-Id: I660629a8b8fa1c2bf4fc59d2499ff806aa280449
Reviewed-on: https://chromium-review.googlesource.com/201133
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Lee Campbell <leecam@chromium.org>
Commit-Queue: Lee Campbell <leecam@chromium.org>
4 files changed