It was noticed that the esp32 port didn't build ulab correctly. The
problem was a multiple defintion of the 'mp_hal_stdout_tx_str' and
'mp_hal_stdout_tx_strn_cooked' functions.
They were defined in stdout_helpers.c but also in the
ports/esp32/mphalport.c.
Fixed by removing stdout_helpers.c from the build.
Signed-off-by: Michael O'Cleirigh <michael.ocleirigh@rivulet.ca>
ec79e44502