unix/mphalport.h: Fix build when MICROPY_USE_READLINE=0.
unix/mphalport.h: Fix build when MICROPY_USE_READLINE=0.

If the built-in input() is enabled (which it is by default) then it needs
some form of readline, so supply it with one when MICROPY_USE_READLINE=0.

Fixes issue #5658.

pramasoul/micropython,tobbad/micropython,henriknelson/micropython,pramasoul/micropython,selste/micropython,pramasoul/micropython,MrSurly/micropython,henriknelson/micropython,pozetroninc/micropython,tobbad/micropython,bvernoux/micropython,kerneltask/micropython,bvernoux/micropython,pramasoul/micropython,bvernoux/micropython,MrSurly/micropython,kerneltask/micropython,selste/micropython,henriknelson/micropython,pozetroninc/micropython,MrSurly/micropython,kerneltask/micropython,selste/micropython,henriknelson/micropython,tobbad/micropython,selste/micropython,pramasoul/micropython,pozetroninc/micropython,bvernoux/micropython,adafruit/circuitpython,MrSurly/micropython,pozetroninc/micropython,selste/micropython,pozetroninc/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,kerneltask/micropython,MrSurly/micropython,adafruit/circuitpython,kerneltask/micropython,henriknelson/micropython,tobbad/micropython,tobbad/micropython