Address symlink attack on dev_debug_vboot.
Address symlink attack on dev_debug_vboot.

Two things here: Use mktemp to create a unique and new temporary directory
to work in, and copy the published log file to a known path in a way that
can't be redirected with symlinks.

There are also a couple of minor tweaks to cleanup a little bit rot in the
information that the script provides.

BUG=chromium-os:8947
TEST=manual

Boot, wait 60 seconds, look for "/tmp/debug_vboot_noisy.log". It should
exist and contain useful and interesting data.

Change-Id: Iff9c5c86802ab7fcf3342e82ba128a1795dba16d

R=rspangler@chromium.org,wad@chromium.org,gauravsh@chromium.org

Review URL: http://codereview.chromium.org/6824018

coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,ionave/seismograph,ccaapton/vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,ccaapton/vboot_reference,ccaapton/vboot_reference,coreboot/vboot,ionave/seismograph,marineam/seismograph,ionave/seismograph,coreboot/vboot,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference,acorn-marvell/vboot_reference,marineam/seismograph,ccaapton/vboot_reference