tools/mpy-tool: Make sure that all C-level variables are unique.
tools/mpy-tool: Make sure that all C-level variables are unique.

Fixes issue #2023.

pramasoul/micropython,tralamazza/micropython,adafruit/micropython,adafruit/circuitpython,Timmenem/micropython,chrisdearman/micropython,tuc-osg/micropython,AriZuu/micropython,hiway/micropython,alex-robbins/micropython,ganshun666/micropython,turbinenreiter/micropython,infinnovation/micropython,alex-march/micropython,pozetroninc/micropython,MrSurly/micropython,lowRISC/micropython,chrisdearman/micropython,Peetz0r/micropython-esp32,redbear/micropython,matthewelse/micropython,pozetroninc/micropython,bvernoux/micropython,praemdonck/micropython,redbear/micropython,mhoffma/micropython,Peetz0r/micropython-esp32,puuu/micropython,bvernoux/micropython,emfcamp/micropython,blazewicz/micropython,blazewicz/micropython,AriZuu/micropython,dmazzella/micropython,praemdonck/micropython,puuu/micropython,pfalcon/micropython,matthewelse/micropython,jmarcelino/pycom-micropython,deshipu/micropython,PappaPeppar/micropython,tuc-osg/micropython,torwag/micropython,chrisdearman/micropython,trezor/micropython,Timmenem/micropython,misterdanb/micropython,lowRISC/micropython,micropython/micropython-esp32,tralamazza/micropython,kerneltask/micropython,hosaka/micropython,pozetroninc/micropython,TDAbboud/micropython,bvernoux/micropython,hosaka/micropython,alex-robbins/micropython,TDAbboud/micropython,mpalomer/micropython,toolmacher/micropython,dxxb/micropython,cwyark/micropython,misterdanb/micropython,kerneltask/micropython,selste/micropython,ryannathans/micropython,infinnovation/micropython,SHA2017-badge/micropython-esp32,kerneltask/micropython,infinnovation/micropython,micropython/micropython-esp32,ganshun666/micropython,pfalcon/micropython,pozetroninc/micropython,redbear/micropython,hiway/micropython,MrSurly/micropython-esp32,deshipu/micropython,henriknelson/micropython,MrSurly/micropython-esp32,MrSurly/micropython-esp32,micropython/micropython-esp32,micropython/micropython-esp32,AriZuu/micropython,emfcamp/micropython,chrisdearman/micropython,swegener/micropython,tuc-osg/micropython,hiway/micropython,mpalomer/micropython,misterdanb/micropython,dinau/micropython,praemdonck/micropython,deshipu/micropython,drrk/micropython,henriknelson/micropython,dinau/micropython,ryannathans/micropython,praemdonck/micropython,misterdanb/micropython,drrk/micropython,oopy/micropython,deshipu/micropython,dinau/micropython,jmarcelino/pycom-micropython,dxxb/micropython,mhoffma/micropython,blazewicz/micropython,swegener/micropython,SHA2017-badge/micropython-esp32,blazewicz/micropython,mhoffma/micropython,swegener/micropython,bvernoux/micropython,turbinenreiter/micropython,ryannathans/micropython,matthewelse/micropython,selste/micropython,mhoffma/micropython,trezor/micropython,hosaka/micropython,adafruit/micropython,kerneltask/micropython,alex-march/micropython,PappaPeppar/micropython,ganshun666/micropython,matthewelse/micropython,tralamazza/micropython,PappaPeppar/micropython,selste/micropython,tobbad/micropython,blazewicz/micropython,toolmacher/micropython,trezor/micropython,MrSurly/micropython-esp32,pramasoul/micropython,adafruit/circuitpython,drrk/micropython,ganshun666/micropython,pramasoul/micropython,trezor/micropython,infinnovation/micropython,chrisdearman/micropython,torwag/micropython,MrSurly/micropython,hiway/micropython,alex-robbins/micropython,ganshun666/micropython,emfcamp/micropython,tobbad/micropython,selste/micropython,jmarcelino/pycom-micropython,pfalcon/micropython,SHA2017-badge/micropython-esp32,HenrikSolver/micropython,oopy/micropython,praemdonck/micropython,tuc-osg/micropython,hiway/micropython,AriZuu/micropython,redbear/micropython,deshipu/micropython,tobbad/micropython,adafruit/circuitpython,oopy/micropython,micropython/micropython-esp32,TDAbboud/micropython,HenrikSolver/micropython,jmarcelino/pycom-micropython,Peetz0r/micropython-esp32,TDAbboud/micropython,pramasoul/micropython,mpalomer/micropython,HenrikSolver/micropython,misterdanb/micropython,adafruit/circuitpython,mpalomer/micropython,mpalomer/micropython,dmazzella/micropython,SHA2017-badge/micropython-esp32,alex-robbins/micropython,MrSurly/micropython,toolmacher/micropython,turbinenreiter/micropython,pfalcon/micropython,matthewelse/micropython,turbinenreiter/micropython,tobbad/micropython,SHA2017-badge/micropython-esp32,tuc-osg/micropython,emfcamp/micropython,henriknelson/micropython,PappaPeppar/micropython,dxxb/micropython,cwyark/micropython,puuu/micropython,Peetz0r/micropython-esp32,torwag/micropython,tralamazza/micropython,Timmenem/micropython,lowRISC/micropython,pramasoul/micropython,toolmacher/micropython,adafruit/micropython,MrSurly/micropython,matthewelse/micropython,PappaPeppar/micropython,adafruit/micropython,Peetz0r/micropython-esp32,MrSurly/micropython,AriZuu/micropython,alex-march/micropython,torwag/micropython,cwyark/micropython,dinau/micropython,dinau/micropython,oopy/micropython,selste/micropython,pozetroninc/micropython,drrk/micropython,oopy/micropython,cwyark/micropython,alex-march/micropython,trezor/micropython,infinnovation/micropython,jmarcelino/pycom-micropython,lowRISC/micropython,dmazzella/micropython,tobbad/micropython,alex-march/micropython,henriknelson/micropython,emfcamp/micropython,hosaka/micropython,bvernoux/micropython,adafruit/micropython,Timmenem/micropython,redbear/micropython,HenrikSolver/micropython,pfalcon/micropython,lowRISC/micropython,ryannathans/micropython,puuu/micropython,adafruit/circuitpython,drrk/micropython,mhoffma/micropython,hosaka/micropython,adafruit/circuitpython,swegener/micropython,MrSurly/micropython-esp32,cwyark/micropython,torwag/micropython,puuu/micropython,Timmenem/micropython,swegener/micropython,dmazzella/micropython,ryannathans/micropython,toolmacher/micropython,HenrikSolver/micropython,henriknelson/micropython,kerneltask/micropython,TDAbboud/micropython,dxxb/micropython,turbinenreiter/micropython,alex-robbins/micropython,dxxb/micropython