[inputcontrol] support alternate log dir

When run as the debug daemon, this script cannot write to the user's homedir, so
support logging to the debug daemon's tmpfs as well.

BUG=chromium-os:30740
TEST=Adhoc
mkdir /debugd/touchpad ; /opt/google/touchpad/tpcontrol log alt ; \
    ls /debugd/touchpad

Change-Id: I2981602158eab67df55644826879133f62e76922
Signed-off-by: Elly Jones <ellyjones@chromium.org>
2 files changed