extmod/moduselect: Implement ipoll() method for alloc-free polling.
extmod/moduselect: Implement ipoll() method for alloc-free polling.

Similar to the implementation added to unix port module previously.

puuu/micropython,ryannathans/micropython,adafruit/circuitpython,ryannathans/micropython,alex-robbins/micropython,torwag/micropython,henriknelson/micropython,toolmacher/micropython,dmazzella/micropython,oopy/micropython,HenrikSolver/micropython,Timmenem/micropython,puuu/micropython,henriknelson/micropython,torwag/micropython,lowRISC/micropython,Timmenem/micropython,selste/micropython,AriZuu/micropython,pfalcon/micropython,PappaPeppar/micropython,hiway/micropython,cwyark/micropython,alex-robbins/micropython,toolmacher/micropython,AriZuu/micropython,MrSurly/micropython,chrisdearman/micropython,bvernoux/micropython,SHA2017-badge/micropython-esp32,bvernoux/micropython,micropython/micropython-esp32,micropython/micropython-esp32,pozetroninc/micropython,pozetroninc/micropython,SHA2017-badge/micropython-esp32,MrSurly/micropython-esp32,puuu/micropython,MrSurly/micropython-esp32,ryannathans/micropython,tralamazza/micropython,pramasoul/micropython,bvernoux/micropython,PappaPeppar/micropython,selste/micropython,chrisdearman/micropython,alex-robbins/micropython,pozetroninc/micropython,adafruit/circuitpython,toolmacher/micropython,swegener/micropython,swegener/micropython,trezor/micropython,MrSurly/micropython-esp32,alex-robbins/micropython,AriZuu/micropython,chrisdearman/micropython,chrisdearman/micropython,oopy/micropython,blazewicz/micropython,lowRISC/micropython,trezor/micropython,adafruit/micropython,infinnovation/micropython,cwyark/micropython,toolmacher/micropython,PappaPeppar/micropython,infinnovation/micropython,MrSurly/micropython,pramasoul/micropython,oopy/micropython,kerneltask/micropython,infinnovation/micropython,trezor/micropython,adafruit/circuitpython,oopy/micropython,adafruit/circuitpython,deshipu/micropython,MrSurly/micropython-esp32,kerneltask/micropython,SHA2017-badge/micropython-esp32,pozetroninc/micropython,pramasoul/micropython,hiway/micropython,infinnovation/micropython,TDAbboud/micropython,swegener/micropython,pozetroninc/micropython,puuu/micropython,adafruit/micropython,dmazzella/micropython,micropython/micropython-esp32,tralamazza/micropython,puuu/micropython,henriknelson/micropython,alex-robbins/micropython,trezor/micropython,deshipu/micropython,lowRISC/micropython,adafruit/micropython,kerneltask/micropython,adafruit/circuitpython,tralamazza/micropython,oopy/micropython,HenrikSolver/micropython,cwyark/micropython,tobbad/micropython,dmazzella/micropython,blazewicz/micropython,TDAbboud/micropython,SHA2017-badge/micropython-esp32,hiway/micropython,tobbad/micropython,TDAbboud/micropython,pramasoul/micropython,HenrikSolver/micropython,bvernoux/micropython,MrSurly/micropython,adafruit/circuitpython,lowRISC/micropython,pfalcon/micropython,adafruit/micropython,Timmenem/micropython,micropython/micropython-esp32,kerneltask/micropython,pfalcon/micropython,blazewicz/micropython,blazewicz/micropython,SHA2017-badge/micropython-esp32,torwag/micropython,MrSurly/micropython,Timmenem/micropython,toolmacher/micropython,adafruit/micropython,swegener/micropython,TDAbboud/micropython,cwyark/micropython,PappaPeppar/micropython,chrisdearman/micropython,TDAbboud/micropython,ryannathans/micropython,deshipu/micropython,lowRISC/micropython,HenrikSolver/micropython,AriZuu/micropython,cwyark/micropython,henriknelson/micropython,blazewicz/micropython,Timmenem/micropython,ryannathans/micropython,MrSurly/micropython-esp32,PappaPeppar/micropython,torwag/micropython,micropython/micropython-esp32,hiway/micropython,dmazzella/micropython,pfalcon/micropython,trezor/micropython,hiway/micropython,MrSurly/micropython,swegener/micropython,pramasoul/micropython,pfalcon/micropython,tobbad/micropython,AriZuu/micropython,torwag/micropython,selste/micropython,bvernoux/micropython,tobbad/micropython,tralamazza/micropython,selste/micropython,tobbad/micropython,infinnovation/micropython,deshipu/micropython,selste/micropython,henriknelson/micropython,HenrikSolver/micropython,kerneltask/micropython,deshipu/micropython