py/mpprint: Support "%lx" format on 64-bit systems.
py/mpprint: Support "%lx" format on 64-bit systems.

Before that, the output was truncated to 32 bits. Only "%x" format is
handled, because a typical use is for addresses.

This refactor actually decreased x86_64 code size by 30 bytes.

pfalcon/micropython,blazewicz/micropython,selste/micropython,ryannathans/micropython,ryannathans/micropython,adafruit/micropython,tobbad/micropython,selste/micropython,selste/micropython,dmazzella/micropython,pfalcon/micropython,ryannathans/micropython,selste/micropython,kerneltask/micropython,swegener/micropython,bvernoux/micropython,henriknelson/micropython,pramasoul/micropython,bvernoux/micropython,pramasoul/micropython,pfalcon/micropython,swegener/micropython,pozetroninc/micropython,bvernoux/micropython,henriknelson/micropython,tralamazza/micropython,bvernoux/micropython,dmazzella/micropython,ryannathans/micropython,adafruit/circuitpython,swegener/micropython,MrSurly/micropython,ryannathans/micropython,pozetroninc/micropython,adafruit/circuitpython,tralamazza/micropython,trezor/micropython,kerneltask/micropython,kerneltask/micropython,swegener/micropython,infinnovation/micropython,infinnovation/micropython,tobbad/micropython,tralamazza/micropython,bvernoux/micropython,trezor/micropython,adafruit/micropython,trezor/micropython,henriknelson/micropython,adafruit/circuitpython,MrSurly/micropython,MrSurly/micropython,henriknelson/micropython,pozetroninc/micropython,pfalcon/micropython,trezor/micropython,adafruit/circuitpython,selste/micropython,pramasoul/micropython,adafruit/micropython,dmazzella/micropython,kerneltask/micropython,adafruit/circuitpython,pozetroninc/micropython,infinnovation/micropython,tobbad/micropython,swegener/micropython,pfalcon/micropython,MrSurly/micropython,tralamazza/micropython,kerneltask/micropython,tobbad/micropython,blazewicz/micropython,blazewicz/micropython,adafruit/micropython,pramasoul/micropython,adafruit/micropython,infinnovation/micropython,adafruit/circuitpython,blazewicz/micropython,blazewicz/micropython,MrSurly/micropython,pozetroninc/micropython,dmazzella/micropython,infinnovation/micropython,pramasoul/micropython,trezor/micropython,tobbad/micropython,henriknelson/micropython