py/emitbc: Produce correct line number info for large bytecode chunks.
py/emitbc: Produce correct line number info for large bytecode chunks.

Previous to this patch, for large chunks of bytecode that originated from
a single source-code line, the bytecode-line mapping would generate
something like (for 42 bytecode bytes and 1 line):

  BC_SKIP=31  LINE_SKIP=1
  BC_SKIP=11  LINE_SKIP=0

This would mean that any errors in the last 11 bytecode bytes would be
reported on the following line.  This patch fixes it to generate instead:

  BC_SKIP=31  LINE_SKIP=0
  BC_SKIP=11  LINE_SKIP=1

toolmacher/micropython,blazewicz/micropython,ryannathans/micropython,puuu/micropython,Timmenem/micropython,ryannathans/micropython,blazewicz/micropython,oopy/micropython,oopy/micropython,pfalcon/micropython,pramasoul/micropython,infinnovation/micropython,hiway/micropython,MrSurly/micropython-esp32,selste/micropython,alex-robbins/micropython,chrisdearman/micropython,tobbad/micropython,henriknelson/micropython,pramasoul/micropython,AriZuu/micropython,AriZuu/micropython,deshipu/micropython,pozetroninc/micropython,toolmacher/micropython,pozetroninc/micropython,adafruit/circuitpython,AriZuu/micropython,HenrikSolver/micropython,PappaPeppar/micropython,ryannathans/micropython,MrSurly/micropython,Peetz0r/micropython-esp32,deshipu/micropython,adafruit/circuitpython,infinnovation/micropython,infinnovation/micropython,tralamazza/micropython,adafruit/circuitpython,PappaPeppar/micropython,chrisdearman/micropython,pfalcon/micropython,trezor/micropython,swegener/micropython,hiway/micropython,MrSurly/micropython,SHA2017-badge/micropython-esp32,SHA2017-badge/micropython-esp32,micropython/micropython-esp32,pozetroninc/micropython,tobbad/micropython,puuu/micropython,pfalcon/micropython,AriZuu/micropython,swegener/micropython,Peetz0r/micropython-esp32,pramasoul/micropython,MrSurly/micropython,TDAbboud/micropython,puuu/micropython,pramasoul/micropython,dmazzella/micropython,deshipu/micropython,adafruit/micropython,toolmacher/micropython,Timmenem/micropython,swegener/micropython,bvernoux/micropython,MrSurly/micropython-esp32,torwag/micropython,SHA2017-badge/micropython-esp32,lowRISC/micropython,deshipu/micropython,torwag/micropython,alex-robbins/micropython,trezor/micropython,PappaPeppar/micropython,TDAbboud/micropython,MrSurly/micropython-esp32,toolmacher/micropython,ryannathans/micropython,alex-robbins/micropython,kerneltask/micropython,dmazzella/micropython,infinnovation/micropython,TDAbboud/micropython,pramasoul/micropython,selste/micropython,oopy/micropython,pozetroninc/micropython,TDAbboud/micropython,trezor/micropython,chrisdearman/micropython,SHA2017-badge/micropython-esp32,chrisdearman/micropython,bvernoux/micropython,henriknelson/micropython,Peetz0r/micropython-esp32,MrSurly/micropython,bvernoux/micropython,adafruit/micropython,henriknelson/micropython,blazewicz/micropython,adafruit/micropython,torwag/micropython,hiway/micropython,MrSurly/micropython-esp32,selste/micropython,Peetz0r/micropython-esp32,pfalcon/micropython,alex-robbins/micropython,ryannathans/micropython,selste/micropython,hiway/micropython,kerneltask/micropython,kerneltask/micropython,tralamazza/micropython,HenrikSolver/micropython,henriknelson/micropython,oopy/micropython,lowRISC/micropython,deshipu/micropython,lowRISC/micropython,micropython/micropython-esp32,torwag/micropython,tobbad/micropython,cwyark/micropython,henriknelson/micropython,puuu/micropython,puuu/micropython,oopy/micropython,PappaPeppar/micropython,trezor/micropython,AriZuu/micropython,blazewicz/micropython,kerneltask/micropython,torwag/micropython,tobbad/micropython,dmazzella/micropython,micropython/micropython-esp32,TDAbboud/micropython,alex-robbins/micropython,Timmenem/micropython,bvernoux/micropython,adafruit/circuitpython,infinnovation/micropython,trezor/micropython,adafruit/circuitpython,cwyark/micropython,hiway/micropython,blazewicz/micropython,SHA2017-badge/micropython-esp32,Timmenem/micropython,PappaPeppar/micropython,toolmacher/micropython,pozetroninc/micropython,adafruit/micropython,bvernoux/micropython,MrSurly/micropython-esp32,pfalcon/micropython,swegener/micropython,HenrikSolver/micropython,chrisdearman/micropython,HenrikSolver/micropython,tralamazza/micropython,kerneltask/micropython,selste/micropython,tralamazza/micropython,micropython/micropython-esp32,lowRISC/micropython,Timmenem/micropython,adafruit/circuitpython,swegener/micropython,MrSurly/micropython,tobbad/micropython,cwyark/micropython,lowRISC/micropython,dmazzella/micropython,cwyark/micropython,cwyark/micropython,HenrikSolver/micropython,adafruit/micropython,Peetz0r/micropython-esp32,micropython/micropython-esp32