servod ec3po: Update third_party/hdctools/ side of ec3po to use threadproc_shim.py.

This removes direct use of the multiprocessing module from the
third_party/hdctools/ side of ec3po, thereby removing its direct use from
servod.  Once this is checked in, threadproc_shim.py can be updated with
threading-oriented implementations.

BRANCH=none
BUG=b:79684405
CQ-DEPEND=CL:1278502
TEST=With a servo_micro connected to an octopus_ite, functionality
involving the EC console continues to work.  I tested dut-control
ec_uart_pty (including using the UART with minicom), dut_i2c_mux,
enable_ite_dfu, get_ite_chipid commands.  Additionally, servod shutdown via
either ctrl+c or SIGTERM still happens correctly, without any delay,
leftover processes, or tracebacks.

Change-Id: I5c7593c009c8db927db4142ada2153d9679cb5c3
Signed-off-by: Matthew Blecker <matthewb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1279118
Reviewed-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
1 file changed